CCNA 2 v6.0 – CCENT (ICND1) Practice Certification Exam Answers

1. How does a switch differ from a hub?

  • A switch does not induce any latency into the frame transfer time.
  • A switch tracks MAC addresses of directly-connected devices.
  • A switch operates at a lower, more efficient layer of the OSI model.
  • A switch decreases the number of broadcast domains.
  • A switch decreases the number of collision domains.

Explanation: Some of the features and functions of a switch include: A switch is essentially a fast, multi-port bridge, which can contain dozens of ports. Rather than creating two collision domains, each port creates its own collision domain. In a network of twenty nodes, twenty collision domains exist if each node is plugged into its own switch port. If an uplink port is included, one switch creates twenty-one single-node collision domains. A switch dynamically builds and maintains a Content-Addressable Memory (CAM) table, holding all of the necessary MAC information for each port. For a detailed description of how switches operate, and their key differences to hubs, see the reference link below. http://www.cisco.com/ warp/public/473/lan-switch-cisco.shtml

2. What must occur before a workstation can exchange HTTP packets with a web server?

  • A UDP connection must be established between the workstation and its default gateway.
  • A UDP connection must be established between the workstation and the web server.
  • A TCP connection must be established between the workstation and its default gateway.
  • A TCP connection must be established between the workstation and the web server.
  • An ICMP connection must be established between the workstation and its default gateway.
  • An ICMP connection must be established between the workstation and the web server.

Explanation: HTTP uses TCP port 80.
http://pentestlab.wordpress.com/2012/03/05/common-tcpip-ports/

3. How does TCP differ from UDP? (Choose two.)

  • TCP provides best effort delivery.
  • TCP provides synchronized communication.
  • TCP segments are essentially datagrams.
  • TCP provides sequence numbering of packets.
  • TCP uses broadcast delivery.

Explanation: TCP differs from UDP in the following ways: TCP provides best effort delivery.
TCP provides synchronized communication. TCP segments are essentially datagrams. TCP provides sequence numbering of packets. TCP uses broadcast delivery.

4. A workstation has just resolved a browser URL to the IP address of a server.

What protocol will the workstation now use to determine the destination MAC address to be placed into frames directed toward the server?

  • HTTP
  • DNS
  • DHCP
  • RARP
  • ARP

5. Refer to the exhibit. Host A is sending a packet to Host B for the first time. What destination MAC address will Host A use in the ARP request?

  • 192.168.0.1
  • 172.16.0.50
  • 00-17-94-61-18-b0
  • 00-19-d3-2d-c3-b2
  • ff-ff-ff-ff-ff-ff
  • 255.255.255.255

Explanation: For the initial communication, Host A will send a broadcast ARP (all F’s) to determine the correct address to use to reach the destination.

6. The network manager has requested a 300-workstation expansion of the network. The workstations are to be installed in a single broadcast domain, but each workstation must have its own collision domain. The expansion is to be as cost-effective as possible while still meeting the requirements. Which three items will adequately fulfill the request? (Choose three).

  • one IP subnet with a mask of 255.255.254.0
  • two IP subnets with a mask of 255.255.255.0
  • seven 48-port hubs
  • seven 48-port switches
  • one router interface
  • seven router interfaces

Explanation: of 255.255.254.0 can absorb 510 hosts being 23 bits mask and also 7*48 port switches can handle this much hosts and router interface is required to be minimum to avoid unnecessary wastage hence the answers.

7. What are two common TCP applications? (Choose two.)

  • TFTP
  • SMTP
  • SNMP
  • FTP
  • DNS

Explanation: SMTP uses TCP port 25, while FTP uses TCP ports 20 and 21. http://pentestlab.wordpress.com/2012/03/05/common-tcpip-ports/

8. Which method does a connected trunk port use to tag VLAN traffic?

  • IEEE 802 1w
  • IEEE 802 1D
  • IEEE 802 1Q
  • IEEE 802 1p

Explanation: IEEE 802.1Q is the networking standard that supports virtual LANS (VLANS) on an Ethernet network. When a frame enters the VLAN-aware portion of the network (a trunk link, for example), a VLAN ID tag is added to represent the VLAN membership of that frame. The picture below shows how VLAN tag is added and removed while going through the network. http://www.cisco.com/c/en/us/support/docs/lan-switching/8021q/17056-741-4.html

9. Which two statements describe the operation of the CSMA/CD access method? (Choose two.)

  • In a CSMA/CD collision domain, multiple stations can successfully transmit data simultaneously.
  • In a CSMA/CD collision domain, stations must wait until the media is not in use before transmitting
  • The use of hubs to enlarge the size of collision domains is one way to improve the operation of the CSMA/CD access method.
  • After a collision, the station that detected the collision has first priority to resend the lost data.
  • After a collision, all stations run a random backoff algorithm. When the backoff delay period has expired, all stations have equal priority to transmit data.
  • After a collision, all stations involved run an identical backoff algorithm and then synchronize with each other prior to transmitting data.

Explanation: Ethernet networking uses Carrier Sense Multiple Access with Collision Detect (CSMA/CD), a protocol that helps devices share the bandwidth evenly without having two devices transmit at the same time on the network medium. CSMA/CD was created to overcome the problem of those collisions that occur when packets are transmitted simultaneously from different nodes. And trust me, good collision management is crucial, because when a node transmits in a CSMA/CD network, all the other nodes on the network receive and examine that transmission. Only bridges and routers can effectively prevent a transmission from propagating throughout the entire network! So, how does the CSMA/CD protocol work? Like this: when a host wants to transmit over the network, it first checks for the presence of a digital signal on the wire. If all is clear (no other host is transmitting), the host will then proceed with its transmission. But it doesn’t stop there. The transmitting host constantly monitors the wire to make sure no other hosts begin transmitting. If the host detects another signal on the wire, it sends out an extended jam signal that causes all nodes on the segment to stop sending data (think, busy signal). The nodes respond to that jam signal by waiting a while before attempting to transmit again. Backoff algorithms determine when the colliding stations can retransmit. If collisions keep occurring after 15 tries, the nodes attempting to transmit will then time out.

10. According to the command output also shown in the exhibit, how will SwitchA handle this frame?

  • It will drop the frame.
  • It will forward the frame out port Fa0/6 only.
  • It will forward the frame out port Fa0/3 only.
  • It will flood the frame out all ports.
  • It will flood the frame out all ports except Fa0/3

Explanation: Switches keep the learned MAC addresses in a table, so that when a frame comes in with a destination MAC address that the switch has already learned, it will forward it to that port only. If a frame comes in with a destination MAC that is not already in the MAC address table, then the frame will be flooded to all ports except for the one that it came in on. In this case, Switch A already knows that 00b0.d0da.cb56 resides on port fa0/6, so it will forward the from out that port.

11. Refer to the exhibit. The exhibit is showing the topology and the MAC address table. Host A sends a data frame to host D. What will the switch do when it receives the frame from host A?

  • The switch will add the source address and port to the MAC address table and forward the frame to host D.
  • The switch will discard the frame and send an error message back to host A.
  • The switch will flood the frame out of all ports except for port Fa0/3.
  • The switch will add the destination address of the frame to the MAC address table and forward the frame to host D.

Explanation: When switch receives the data frame from the host not having the MAC address already on the MAC table, it will add the MAC address to source port on MAC address table and sends the data frame.

12. Refer to the exhibit. If the resume command is entered after the sequence that is shown in the exhibit, which router prompt will be displayed?

  • Router1>
  • Router1#
  • Router2>
  • Router2#

Explanation: The Ctrl-Shift-6 x command suspends the telnet session and hence the prompt will again be Router2>

13. Refer to the exhibit. Which default gateway address should be assigned to HostA?

  • 192.168.1.1
  • 192.168.1.65
  • 192.168.1.66
  • 192.168.1.129
  • 10.1.1.1
  • 10.1.1.2

Explanation: It should be one less than the switch IP to which it is connected so it will be B.

14. Refer to the exhibit. A network has been planned as shown. Which three statements accurately describe the areas and devices in the network plan? (Choose three.)

  • Network Device A is a switch.
  • Network Device B is a switch.
  • Network Device A is a hub.
  • Network Device B is a hub.
  • Area 1 contains a Layer 2 device.
  • Area 2 contains a Layer 2 device.

Explanation: Switches use a separate collision domain for each port, so device A must be a switch. Hubs, however, place all ports in the same collision domain so device B is a hub. Switches reside in layer 2 while hubs are layer 1 devices.

15. Which two options will help to solve the problem of a network that is suffering a broadcast storm? (Choose two.)

  • a bridge
  • a router
  • a hub
  • a Layer 3 switch
  • an access point

Explanation: Routers and layer 3 switches will not propagate broadcast traffic beyond the local segment, so the use of these devices is the best method for eliminating broadcast storms.

16. Refer to the exhibit. All devices attached to the network are shown. How many collision domains are present in this network?

  • 2
  • 3
  • 6
  • 9
  • 15

Explanation: A switch uses a separate collision domain for each port so there are a total of 9 for each device shown. In addition to this, the switch to switch connections (3) are a separate collision domain. Finally, we add the switch to router connections (2) and the router to router connection (1) for a total of 15.

17. What does a host on an Ethernet network do when it is creating a frame and it does not have the destination address?

  • drops the frame
  • sends out a Layer 3 broadcast message
  • sends a message to the router requesting the address
  • sends out an ARP request with the destination IP address

Explanation: Understanding this concept is prime for understanding that when switch receives the data frame from the host not having the MAC address already in the MAC table, it will add the MAC address to the source port on the MAC address table and sends the data frame. If the switch already has the MAC address in it’s table for the destination, it will forward the frame directly to the destination port. If it was not already in it’s MAC table, then they frame would have been flooded out all ports except for the port that it came from.

18. Refer to the exhibit. The ports that are shown are the only active ports on the switch. The MAC address table is shown in its entirety. The Ethernet frame that is shown arrives at the switch. What two operations will the switch perform when it receives this frame? (Choose two.)

  • The MAC address of 0000.00aa aaaa will be added to the MAC address table.
  • The MAC address of 0000.00dddddd will be added to the MAC address table.
  • The frame will be forwarded out port fa0/3 only. I
  • The frame will be forwarded out fa0/1, fa0/2, and fa0/3.
  • The frame will be forwarded out all the active ports.

Explanation: If the switch already has the MAC address in its table for the destination, it will forward the frame directly to the destination port. If it was not already in its MAC table, then they frame would have been flooded out all ports except for the port that it came from.It will also add the MAC address of the source device to its MAC address table

19. A switch has 48 ports and 4 VLANs. How many collision and broadcast domains exist on the switch (collision, broadcast)?

  • 4, 48
  • 48, 4
  • 48, 1
  • 1, 48
  • 4,1

Explanation: A switch uses a separate collision domain for each port, and each VLAN is a separate broadcast domain.

20. Which address type does a switch use to make selective forwarding decisions?

  • source IP address
  • destination IP address
  • source and destination IP address
  • source MAC address
  • destination MAC address

Explanation: Switches analyze the destination MAC to make its forwarding decision since it is a layer 2 device. Routers use the destination IP address to make forwarding decisions.

21. Refer to the exhibit. The MAC address table is shown in its entirety. The Ethernet frame that is shown arrives at the switch. What two operations will the switch perform when it receives this frame? (Choose two.)

  • The switch will not forward a frame with this destination MAC address.
  • The MAC address of 0000.00 aa aaaa will be added to the MAC Address Table.
  • The MAC address of ffff.ffff. ffff will be added to the MAC address table.
  • The frame will be forwarded out all active switch ports except for port fa0/0.
  • The frame will be forwarded out fa0/0 and fa0/1 only.
  • The frame will be forwarded out all the ports on the switch.

Explanation: If the switch already has the MAC address in its table for the destination, it will forward the frame directly to the destination port. If it was not already in its MAC table, then they frame would have been flooded out all ports except for the port that it came from.

22. On a Cisco switch, which protocol determines if an attached VolP phone is from Cisco or from another vendor?

  • RTP
  • TCP
  • CDP
  • UDP

Explanation: The Cisco Unified IP Phone uses CDP to communicate information such as auxiliary VLAN ID, per port power management details, and Quality of Service (QoS) configuration information with the Cisco Catalyst switch.

23. Refer to the exhibit. What must be configured to establish a successful connection from Host A to switch SW-A through router RT-A?

  • VLAN 1 on RT-A
  • IP routing on SW-A
  • default gateway on SW-A
  • crossover cable connecting SW-A and RT-A

Explanation: In order for the switch to reach networks that are not local, such as networks attached to different interfaces of the router, it will need to set its default gateway to be the IP address of the attached router.

24. A switch receives a frame on one of its ports. There is no entry in the MAC address table for the destination MAC address. What will the switch do with the frame?

  • drop the frame
  • forward it out of all ports except the one that received it
  • forward it out of all ports
  • store it until it learns the correct port

Explanation: Understanding this concept is prime for understanding that when switch receives the data frame from the host not having the MAC address already in the MAC table, it will add the MAC address to the source port on the MAC address table and sends the data frame. If the switch already has the MAC address in it’s table for the destination, it will forward the frame directly to the destination port. If it was not already in it’s MAC table, then they frame would have been flooded out all ports except for the port that it came from.

25. At which layer of the OSI model does the protocol that provides the information that is displayed by the show cdp neighbors command operate?

  • application
  • transport
  • network
  • physical
  • data link

Explanation: CDP is a device discovery protocol that runs over Layer 2 (the data link layer) on all Cisco manufactured devices (routers, bridges, access servers, and switches) and allows network management applications to discover Cisco devices that are neighbors of already known devices. With CDP, network management applications can learn the device type and the Simple Network Management Protocol (SNMP) agent address of neighboring devices running lower-layer, transparent protocols.

26. Which two characteristics apply to Layer 2 switches? (Choose two.)

  • increases the number of collision domains
  • decreases the number of collision domains
  • implements VLAN
  • decreases the number of broadcast domains
  • uses the IP address to make decisions for forwarding data packets

Explanation: Layer 2 switches offer a number of benefits to hubs, such as the use of VLANs and each switch port is in its own separate collision domain, thus eliminating collisions on the segment.

27. Which two commands will display the current IP address and basic Layer 1 and 2 status of an interface? (Choose two.)

  • router#show version
  • router#show ip interface
  • router#show protocols
  • router#show controllers
  • router#show running-config

28. Which two characteristics describe the access layer of the hierarchical network design model? (Choose two.)

  • layer 3 support
  • port security
  • redundant components
  • VLANs
  • PoE

Explanation:

The primary function of an access-layer is to provide network access to the end user. The hardware and software attributes of the access layer that support high availability include security services for additional security against unauthorized access to the network through the use of tools such as 802.1x, port security, DHCP snooping, Dynamic ARP Inspection, and IP Source Guard.

29. Refer to the topology and switching table shown in the graphic. Host B sends a frame to Host C. What will the switch do with the frame?

  • drop the frame
  • send the frame out all ports except port 0/2
  • return the frame to Host B
  • send an ARP request for Host C
  • send an ICMP Host Unreachable message to Host B
  • record the destination MAC address in the switching table and send the frame directly to Host C

Explanation: An Ethernet switch appears to use the same logic as a transparent bridge. However, the internal logic of the switch is optimized for performing the basic function of choosing when to forward and when to filter a frame. Just as with a transparent bridge, the basic logic of a LAN switch is as follows:

Step 1: A frame is received.
Step 2: If the destination is a broadcast or multicast, forward on all ports.
Step 3: If the destination is a unicast and the address is not in the address table, forward on all ports.
Step 4: If the destination is a unicast and the address is in the address table, forward the frame out the associated port, unless the MAC address is associated with the incoming port.

30. What is the purpose of assigning an IP address to a switch?

  • provides local hosts with a default gateway address
  • allows remote management of the switch
  • allows the switch to respond to ARP requests between two hosts
  • ensures that hosts on the same LAN can communicate with each other

Explanation: Switch is a layer 2 device and doesn’t use network layer for packet forwarding. The IP address may be used only for administrative purposes such as Telnet access or for network management purposes.

31. Which three statements are true about the operation of a full-duplex Ethernet network? (Choose three.)

  • There are no collisions in full-duplex mode.
  • A dedicated switch port is required for each full-duplex node.
  • Ethernet hub ports are preconfigured for full-duplex mode.
  • In a full-duplex environment, the host network card must check for the availability of the network media before transmitting.
  • The host network card and the switch port must be capable of operating in full-duplex mode.

Explanation: Half-duplex Ethernet is defined in the original 802.3 Ethernet and Cisco says you only use one wire pair with a digital signal running in both directions on the wire. It also uses the CSMA/CD protocol to help prevent collisions and to permit retransmitting if a collision does occur. If a hub is attached to a switch, it must operate in half-duplex mode because the end stations must be able to detect collisions. Half-duplex Ethernet–typically 10BaseT-is only about 30 to 40 percent efficient as Cisco sees it, because a large 10BaseT network will usually only give you 3- to 4Mbps–at most. Full-duplex Ethernet uses two pairs of wires, instead of one wire pair like half duplex. Also, full duplex uses a point-to-point connection between the transmitter of the transmitting device and the receiver of the receiving device, which means that with full-duplex data transfer, you get a faster data transfer compared to half duplex. And because the transmitted data is sent on a different set of wires than the received data, no collisions occur. The reason you don’t need to worry about collisions is because now Full-duplex Ethernet is like a freeway with multiple lanes instead of the single-lane road provided by half duplex. Full-duplex Ethernet is supposed to offer 100 percent efficiency in both directions, this means you can get 20Mbps with a 10Mbps Ethernet running full duplex, or 200Mbps for FastEthernet.

32. Which router command can be used to determine the status of Serial 0/0?

  • show ip route
  • show interfaces
  • show s0/0 status
  • debug s0/0
  • show run
  • show version

33. What is the subnet address of 172.16.159.159/22?

  • 172.16.0.0
  • 172.16.128.0
  • 172.16.156.0
  • 172.16.159.0
  • 172.16.159.128
  • 172.16.192.0

Explanation:

Converting to binary format it comes to
11111111.11111111.11111100.00000000 or
255.255.252.0
Starting with 172.16.0.0 and having increment of 4 we get.

34. An administrator is working with the 192.168.4.0 network, which has been subnetted with a /26 mask. Which two addresses can be assigned to hosts within the same subnet? (Choose two.)

  • 192.168.4.61
  • 192.168.4.63
  • 192.168.4.67
  • 192.168.4.125
  • 192.168.4.128
  • 192.168.4.132

Explanation: Only the values of host with 67 and 125 fall within the range of /26 CIDR subnet mask, all others lie beyond it.

35. Refer to the exhibit. The internetwork is using subnets of the address 192.168.1.0 with a subnet mask of 255.255.255.224. The routing protocol in use is RIP version 1. Which address could be assigned to the FastEthernet interface on RouterA?

  • 192.168.1.31
  • 192.168.1.64
  • 192.168.1.127
  • 192.168.1.190
  • 192.168.1.192

[/alert-success]Explanation:

Subnet mask 255.255.255.224 with CIDR of /27 which results in 32 hosts per. 192.168.1.31 is the broadcast address for sunbet ‘0’ 192.168.1.64 is the network address for subnet ‘2’ 192.168.1.127 is the broadcast address for subnet ‘3’ 192.168.1.192 is the network address for subnet ‘6’

[/alert-success]

36. What is the network address for the host with IP address 192.168.23.61/28?

  • 192.168.23.0
  • 192.168.23.32
  • 192.168.23.48
  • 192.168.23.56
  • 192.168.23.60

Explanation: convert bit-length prefix to quad-dotted decimal representation, then from it find the number of bits used for subnetting you can find previously calculated number of subnets by separating subnets each having value of last bit used for subnet masking Find that your IP address is in which subnet, that subnet’s first address is network address and last address is broadcast address. Based on above steps the answer is option C.

37. What is the best practice when assigning IP addresses in a small office of six hosts?

  • Use a DHCP server that is located at the headquarters.
  • Use a DHCP server that is located at the branch office.
  • Assign the addresses by using the local CDP protocol
  • Assign the addresses statically on each node.

Explanation: Its best to use static addressing scheme where the number of systems is manageable rather than use dynamic protocol as it is easy to operate and manage.

38. Refer to the exhibit. The enterprise has decided to use the network address 172.16.0.0. The network administrator needs to design a classful addressing scheme to accommodate the three subnets, with 30, 40, and 50 hosts, as shown. What subnet mask would accommodate this network?

  • 255.255.255.192
  • 255.255.255.224
  • 255.255.255.240
  • 255.255.255.248
  • 255 255.255.252

Explanation:

Subnet mask Ai.e. 255.255.255.192 with CIDR of /26 which means 64 hosts per subnet which are sufficient to accommodate even the largest subnet of 50 hosts.

39. Which two statements describe the IP address 10.16.3.65/23? (Choose two.)

  • The subnet address is 10.16.3.0 255.255.254.0.
  • The lowest host address in the subnet is 10.16.2.1 255.255.254.0.
  • The last valid host address in the subnet is 10.16.2.254 255.255.254.0
  • The broadcast address of the subnet is 10.16.3.255 255.255.254.0.
  • The network is not subnetted.

Explanation: The mask 255.255.254.0 (/23) used with a Class A address means that there are 15 subnet bits and 9 host bits. The block size in the third octet is 2 (256 – 254). So this makes the subnets in 0, 2, 4,6, etc., all the way to 254. The host 10.16.3.65 is in the 2.0 subnet. The next subnet is 4.0, so the broadcast address for the 2.0 subnet is 3.255. The valid host addresses are 2.1 through 3.254

40. Given a Class CIP address subnetted with a /30 subnet mask, how many valid host IP addresses are available on each of the subnets?

  • 1
  • 2
  • 4
  • 8
  • 252
  • 254

Explanation: /30 CIDR corresponds to mask 55.255.255.252 whose binary is 11111100 which means 6 subnet bits and 2 host bits which means 62 subnets and 2 hosts per subnet.

41. Which one of the following IP addresses is the last valid host in the subnet using mask 255.255.255.224?

  • 192.168.2.63
  • 192.168.2.62
  • 192.168.2.61
  • 192.168.2.60
  • 192.168.2.32

Explanation: With the 224 there are 8 networks with increments of 32 One of these is 32 33 62 63 where 63 is broadcast so 62 is last valid host out of given choices.

42. An administrator is in the process of changing the configuration of a router. What command will allow the administrator to check the changes that have been made prior to saving the new configuration?

  • Router# show startup-config
  • Router# show current-config
  • Router# show running-config
  • Router# show memory
  • Router# show flash
  • Router# show processes

Explanation: This command followed by the appropriate parameter will show the running config hence the admin will be able to see what changes have been made, and then they can be saved.

43. Which statements accurately describe CDP? (Choose three.)

  • CDP is an IEEE standard protocol.
  • CDP is a Cisco proprietary protocol.
  • CDP is a datalink layer protocol.
  • CDP is a network layer protocol.
  • CDP can discover directly connected neighboring Cisco devices.
  • CDP can discover Cisco devices that are not directly connected.

Explanation: CDP (Cisco Discovery Protocol) is a proprietary protocol designed by Cisco to help administrators collect information about both locally attached and remote devices. By using CDP, you can gather hardware and protocol information about neighbor devices containing useful info for troubleshooting and documenting the network.

44. On a live network, which commands will verify the operational status of router interfaces? (Choose two.)

  • Router# show interfaces
  • Router# show ip protocols
  • Router# debug interface
  • Router# show ip interface brief
  • Router# show start

Explanation: Both these commands will show the current status of the interfaces, either in show or debug mode both will display the information.

45. Which router command will configure an interface with the IP address 10.10.80.1/19?

  • router(config-if)# ip address 10.10.80.1/19
  • router(config-if)# ip address 10.10.80.1 255.255.0.0
  • router(config-if)# ip address 10.10.80.1 255.255.255.0
  • router(config-if)# ip address 10.10.80.1 255.255.224.0
  • router(config-if)# ip address 10.10.80.1 255.255.240.0
  • router(config-if)# ip address 10.10.80.1 255.255.255.240

Explanation: 255.255.224 equal /19 in CIDR format hence the answer

46. Refer to the exhibit. If CDP is enabled on all devices and interfaces, which devices will appear in the output of a show cdp neighbors command issued from R2?

  • R2 and R3
  • R1 and R3
  • R3 and S2
  • R1, S1, S2, and R3
  • R1, S1, S2, R3, and S3

Explanation: A Cisco device enabled with CDP sends out periodic interface updates to a multicast address in order to make itself known to neighbors. Since it is a layer two protocol, these packets are not routed. So the devices detected would be immediate connected neighbors.

47. Refer to the exhibit. The two routers have had their startup configurations cleared and have been restarted. At a minimum, what must the administrator do to enable CDP to exchange information between R1 and R2?

  • Configure the router with the cdp enable command.
  • Enter no shutdown commands on the R1 and R2 fa0/1 interfaces.
  • Configure IP addressing and no shutdown commands on both the R1 and R2 fa0/1 interfaces.
  • Configure IP addressing and no shutdown commands on either of the R1 or R2 fa0/1 interfaces.

Explanation: If the shut down commands are not entered, then CDP can exchange information between the two routers, else it would fail.

48. Refer to the exhibit. The network administrator is testing connectivity from the branch router to the newly installed application server. What is the most likely reason for the first ping having a success rate of only 60 percent?

  • The network is likely to be congested, with the result that packets are being intermittently dropped.
  • The branch router had to resolve the application server MAC address.
  • There is a short delay while NAT translates the server IP address.
  • A routing table lookup delayed forwarding on the first two ping packets.
  • The branch router LAN interface should be upgraded to FastEthernet.

Explanation: Initially the MAC address had to be resolved, but later on it was confirmed to ping went straight away

49. What two things does a router do when it forwards a packet? (Choose two.)

  • switches the packet to the appropriate outgoing interfaces
  • computes the destination host address
  • determines the next hop on the path
  • updates the destination IP address
  • forwards ARP requests

Explanation: Without following these two processes namely switching the packet to appropriate interface and telling the packet where to go by providing it with a destination IP address, the purpose of the same would not be solved.

50. Which two of these functions do routers perform on packets? (Choose two.)

  • examine the Layer 2 headers of inbound packets and use that information to determine the next hops for the packets
  • update the Layer 2 headers of outbound packets with the MAC addresses of the next hops
  • examine the Layer 3 headers of inbound packets and use that information to determine the next hops for the packets
  • examine the Layer 3 headers of inbound packets and use that information to determine the complete paths along which the packets will be routed to their ultimate destinations
  • update the Layer 3 headers of outbound packets so that the packets are properly directed to valid next hops
  • update the Layer 3 headers of outbound packets so that the packets are properly directed to their ultimate destinations

Explanation: This is the basic function of the router to receive incoming packets and then forward them to their required destination. This is done by reading layer 3 headers of inbound packets and update the info to layer 2 for further hopping.

51. Refer to the exhibit. Which two statements are correct? (Choose two.)

  • This is a default route.
  • Adding the subnet mask is optional for the ip route command.
  • This will allow any host on the 172.16.1.0 network to reach all known destinations beyond RouterA.
  • This command is incorrect, it needs to specify the interface, such as s0/0/0 rather than an IP address.
  • The same command needs to be entered on RouterA so that hosts on the 172.16.1.0 network can reach network 10.0.0.0.

Explanation: This is obviously the default value for the route which is set between the routers and since it is entered in such a manner that it ensures connectivity between the stub network and any host lying beyond RouterA.

52. Which statements are true regarding ICMP packets? (Choose two.)

  • They acknowledge receipt of TCP segments.
  • They guarantee datagram delivery.
  • TRACERT uses ICMP packets.
  • They are encapsulated within IP datagrams.
  • They are encapsulated within UDP datagrams.

Explanation: Ping may be used to find out whether the local machines are connected to the network or whether a remote site is reachable. This tool is a common network tool for determining the network connectivity which uses ICMP protocol instead of TCP/IP and UDP/IP. This protocol is usually associated with the network management tools which provide network information to network administrators, such as ping and traceroute (the later also uses the UDP/IP protocol). ICMP is quite different from the TCP/IP and UDP/IP protocols. No source and destination ports are included in its packets. Therefore, usual packet-filtering rules for TCP/IP and UDP/IP are not applicable. Fortunately, a special “signature” known as the packet’s Message type is included for denoting the purposes of the ICMP packet. Most commonly used message types are namely, 0, 3, 4, 5, 8, 11, and 12 which represent echo reply, destination unreachable, source quench, redirect, echo request, time exceeded, and parameter problem respectively.

In the ping service, after receiving the ICMP “echo request” packet from the source location, the destination

53. The command ip route 192.168.100.160 255.255.255.224 192.168.10.2 was issued on a router. No routing protocols or other static routes are configured on the router. Which statement is true about this command?

  • The interface with IP address 192.168.10.2 is on this router.
  • The command sets a gateway of last resort for the router.
  • Packets that are destined for host 192.168.100.160 will be sent to 192.168.10.2.
  • The command creates a static route for all IP traffic with the source address
    192.168.100.160.

Explanation: 160 it’s actually network address of /27 so any address within the range of 160 network will be sent to 192.168.10.2

54. Refer to the exhibit. Host A can communicate with Host B but not with Hosts C or D. How can the network administrator solve this problem?

  • Configure Hosts C and D with IP addresses in the 192.168.2.0 network.
  • Install a router and configure a route to route between VLANs 2 and 3.
  • Install a second switch and put Hosts C and D on that switch while Hosts A and B remain on the original switch.
  • Enable the VLAN trunking protocol on the switch.

Explanation: Two VLANs require a router in between otherwise they cannot communicate through a simple switch mechanism

55. Refer to the exhibit. What is the simplest way to configure routing between the regional office network 10.89.0.0/20 and the corporate network?

  • router1(config)#ip route 10.89.0.0 255.255.240.0 10.89.16.2
  • router2(config)#ip route 10.89.3.0 255.255.0.0 10.89.16.2
  • router1(config)#ip route 10.89.0.0 255.255.240.0 10.89.16.1
  • router2(config)#ip route 0.0.0.0 0.0.0.0 10.89.16.1

Explanation: The fourth command makes it possible for all hosts beyond R2 and all hosts beyond R1 to interact with each other, hence it is the most simplest technique.

56. Refer to the exhibit. Which command would you use to configure a static route on Router 1 to network 192.168.202.0/24 with a nondefault administrative distance?

  • router1(config)#ip route 1 192.168.201.1 255.255.255.0 192.168.201.2
  • router1(config)#ip route 192.168.202.0 255.255.255.0 192.168.201.21
  • router1(config)#ip route 5 192.168.202.0 255.255.255.0 192.168.201.2
  • router1(config)#ip route 192.168.202.0 255.255.255.0 192.168.201.2 5

Explanation: Since it has /24 CIDR and it also has a non default administrative distance, the answer has to be option D.

57. What does administrative distance refer to?

  • the cost of a link between two neighboring routers
  • the advertised cost to reach a network
  • the cost to reach a network that is administratively set
  • a measure of the trustworthiness of a routing information source

Explanation: Administrative distance.is the first criterion that a router uses to determine which routing protocol to use if two protocols provide route information for the same destination. Administrative distance is a measure of the trustworthiness of the source of the routing information. The smaller the administrative distance value, the more reliable the protocol.

58. Which IOS command is used to initiate a login into a VTY port on a remote router?

  • router# login
  • router# telnet
  • router# trace
  • router#ping
  • router(config)# line vty 0 5
  • router(config-line)# login

Explanation: VTY ports are telnet ports hence command B will initiate login to the telnet port.

59. In the configuration of NAT, what does the keyword overload signify?

  • When bandwidth is insufficient, some hosts will not be allowed to access network
    translation
  • The pool of IP addresses has been exhausted.
  • Multiple internal hosts will use one IP address to access external network resources.
  • If the number of available IP addresses is exceeded, excess traffic will use the specified address pool.

Explanation: Overload simply means using multiple hosts to access the network using the same translated IP address.

60. What happens when computers on a private network attempt to connect to the Internet through a Cisco router running PAT?

  • The router uses the same IP address but a different TCP source port number for each connection.
  • An IP address is assigned based on the priority of the computer requesting the connection.
  • The router selects an address from a pool of one-to-one address mappings held in the lookup table.
  • The router assigns a unique IP address from a pool of legally registered addresses for the duration of the connection.

Explanation: http://www.cisco.com/en/US/docs/security/asalasa82/configuration/guide/nat_statipat.html Static PAT translations allow a specific UDP or TCP port on a global address to be translated to a specific port on a local address. That is, both the address and the port numbers are translated. Static PAT is the same as static NAT, except that it enables you to specify the protocol (TCP or UDP) and port for the real and mapped addresses. Static PAT enables you to identify the same mapped address across many different static statements, provided that the port is different for each statement. You cannot use the same mapped address for multiple static NAT statements. Port Address Translation makes the PC connect to the Internet but using different TCP source port.

61. When configuring NAT, the Internet interface is considered to be what?

  • local
  • inside
  • global
  • outside

Explanation: Network address translation or NAT requires the Internet to be considered as an outside interface else it won’t serve the purpose it intends to.

62. The ip helper-address command does what?

  • assigns an IP address to a host
  • resolves an IP address from a DNS server
  • relays a DHCP request across networks
  • resolves an IP address overlapping issue

Explanation: When the DHCP client sends the DHCP request packet, it doesn’t have an IP address. So it uses the all-zeroes address, 0.0.0.0, as the IP source address. And it doesn’t know how to reach the DHCP server, so it uses a general broadcast address, 255.255.255.255, for the destination. So the router must replace the source address with its own IP address, for the interface that received the request. And it replaces the destination address with the address specified in the ip helperaddress command. The client device’s MAC address is included in the payload of the original DHCP request packet, so the router doesn’t need to do anything to ensure that the server receives this information.

63. Refer to the exhibit. The network administrator made the entries that are shown and then saved the configuration. From a console connection, what password or password sequence is required for the administrator to access privileged mode on Router1?

  • Cisco
  • sanfran
  • sanjose
  • either cisco or sanfran
  • either cisco or sanjose
  • sanjose and sanfran

Explanation: The enable secret password takes precedence over the enable password, so sanfran will be used.

64. The following commands are entered on the router:

What is the purpose of the last command entered?

  • to require the user to enter an encrypted password during the login process
  • to prevent the vty, console, and enable passwords from being displayed in plain text in the configuration files
  • to encrypt the enable secret password
  • to provide login encryption services between hosts attached to the router

Explanation: Certain types of passwords, such as Line passwords, by default appear in clear text in the configuration file. You can use the service password-encryption command to make them more secure. Once this command is entered, each password configured is automatically encrypted and thus rendered illegible inside the configuration file (much as the Enable/Enable Secret passwords are). Securing Line passwords is doubly important in networks on which TFTP servers are used, because TFTP backup entails routinely moving config files across networks–and config files, of course, contain Line passwords.

65. What is the effect of using the service password-encryption command?

  • Only the enable password will be encrypted.
  • Only the enable secret password will be encrypted.
  • Only passwords configured after the command has been entered will be encrypted.
  • It will encrypt the secret password and remove the enable secret password from the configuration.
  • It will encrypt all current and future passwords.

Explanation: Encryption further adds a level of security to the system as anyone having access to the database of passwords cannot reverse the process of encryption to know the actual passwords which isn’t the case if the passwords are stored simply.

66. An administrator has connected devices to a switch and, for security reasons, wants the dynamically learned MAC addresses from the address table added to the running configuration. What must be done to accomplish this?

  • Enable port security and use the keyword sticky.
  • Set the switchport mode to trunk and save the running configuration.
  • Use the switchport protected command to have the MAC addresses added to the
    configuration
  • Use the no switchport port-security command to allow MAC addresses to be added to the configuration

Explanation: One can configure MAC addresses to be sticky. These can be dynamically learned or manually configured, stored in the address table, and added to the running configuration. If these addresses are saved in the configuration file, the interface does not need to dynamically relearn them when the switch restarts, hence enabling security as desired.

67. A company has placed a networked PC in a lobby so guests can have access to the corporate directory. A security concern is that someone will disconnect the directory PC and re-connect their laptop computer and have access to the corporate network. For the port servicing the lobby, which three configuration steps should be performed on the switch to prevent this? (Choose three.)

  • Enable port security.
  • Create the port as a trunk port.
  • Create the port as an access port.
  • Create the port as a protected port.
  • Set the port security aging time to 0.
  • Statically assign the MAC address to the address table.
  • Configure the switch to discover new MAC addresses after a set time of inactivity.

Explanation: If port security is enabled and the port is only designated as access port, and finally static MAC address is assigned, it ensures that even if a physical connection is done by taking out the directory PC and inserting personal laptop or device, the connection cannot be made to the corporate network, hence ensuring safety.

68. Why would a network administrator configure port security on a switch?

  • to prevent unauthorized Telnet access to a switch port
  • to prevent unauthorized hosts from accessing the LAN
  • to limit the number of Layer 2 broadcasts on a particular switch port
  • block unauthorized access to the switch management interfaces

Explanation: You can use the port security feature to restrict input to an interface by limiting and identifying MAC addresses of the stations allowed to access the port. When you assign secure MAC addresses to a secure port, the port does not forward packets with source addresses outside the group of defined addresses. If you limit the number of secure MAC addresses to one and assign a single secure MAC address, the workstation attached to that port is assured the full bandwidth of the port. If a port is configured as a secure port and the maximum number of secure MAC addresses is reached, when the MAC address of a station attempting to access the port is different from any of the identified secure MAC addresses, a security violation occurs. Also, if a station with a secure MAC address configured or learned on one secure port attempts to access another secure port, a violation is flagged.

69. How can you ensure that only the MAC address of a server is allowed by switch port Fa0/1?

  • Configure port Fa0/1 to accept connections only from the static IP address of the server.
  • Configure the server MAC address as a static entry of port security.
  • Use a proprietary connector type on Fa0/1 that is incomputable with other host connectors.
  • Bind the IP address of the server to its MAC address on the switch to prevent other hosts from spoofing the server IP address.

Explanation: When the MAC address is configured as static entry, no other address is allowed.

70. Refer to the exhibit. A network administrator has configured a Catalyst 2950 switch for remote management by pasting into the console the configuration commands that are shown in the exhibit. However, a Telnet session cannot be successfully established from a remote host. What should be done to fix this problem?

  • Change the first line to interface fastethernet 0/1.
  • Change the first line to interface vlan 0/1.
  • Change the fifth line to ip default-gateway 192.168.17.241.
  • Change the fifth line to ip route 0.0.0.0 0.0.0.0 192.168.17.1.
  • Change the sixth line to line con 0.

Explanation: The default gateway for remote session is 192.168.17.241 and not the one given in the exhibit.

71. Which IP addresses are valid for hosts belonging to the 10.1.160.0/20 subnet? (Choose three.)

  • 10.1.168.0
  • 10.1.176.1
  • 10.1.174.255
  • 10.1.160.255
  • 10.1.160.0
  • 10.1.175.255

Explanation:

All IP address in IP ranges between : 10.1.160.1 and 10.1.175.254 are valid as shown below Address: 10.1.160.0 00001010.00000001.1010 0000 00000000 Netmask:255.255.240.0 = 2011111111.11111111.1111 0000 00000000 Wildcard:0.0.15.25500000000.00000000.0000 1111.11111111

Which implies that

Network: 10.1.160.0/20 00001010-00000001.1010 0000 00000000 HostMin:10.1.160.100001010.00000001.1010 0000 00000001
HostMax: 10.1.175.25400001010.00000001.1010 1111.11111110 Broadcast:10.1.175.25500001010.00000001.1010 1111.11111111

72. Refer to the exhibit. An administrator cannot connect from R1 to R2. To troubleshoot this problem, the administrator has entered the command shown in the exhibit. Based on the output shown, what could be the problem?

  • The serial interface is configured for half duplex.
  • The serial interface does not have a cable attached.
  • The serial interface has the wrong type of cable attached.
  • The serial interface is configured for the wrong frame size.
  • The serial interface has a full buffer.

Explanation: since the output is not forthcoming it shows that the type of cable attached is wrong, though the cable is connected since it shows the cable type. According to the figure DTE cable should connect to R1 on interface but while examining using show controllers serial 0/0 command it showing that a DCE is connected so the wrong type of cable is being used.

73. Refer to the exhibit. A TFTP server has recently been installed in the Atlanta office. The network administrator is located in the NY office and has made a console connection to the NY router. After establishing the connection they are unable to backup the configuration file and IOS of the NY router to the TFTP server. What is the cause of this problem?

  • The NY router has an incorrect subnet mask.
  • The TFTP server has an incorrect IP address.
  • The TFTP server has an incorrect subnet mask.
  • The network administrator computer has an incorrect IP address.

Explanation: The subnet mast of the TFTP server needs to be in tune with the other network requirements else it wont be possible.

74. If a host experiences intermittent issues that relate to congestion within a network while remaining connected, what could cause congestion on this LAN?

  • half-duplex operation
  • broadcast storms
  • network segmentation
  • multicasting

Explanation: A broadcast storm can consume sufficient network resources so as to render the network unable to transport normal traffic.

75. Refer to the exhibit. The junior network support staff provided the diagram as a recommended configuration for the first phase of a four-phase network expansion project. The entire network expansion will have over 1000 users on 14 network segments and has been allocated this IP address space.

192.168.1.1 through 192.168.5.255 
192.168.100.1 through 192.168.100.255

What are three problems with this design? (Choose three.)

  • The AREA 1 IP address space is inadequate for the number of users.
  • The AREA 3 IP address space is inadequate for the number of users.
  • AREA 2 could use a mask of /25 to conserve IP address space.
  • The network address space that is provided requires a single network-wide mask.
  • The router-to-router connection is wasting address space.
  • The broadcast domain in AREA 1 is too large for IP to function.

Explanation: The given IP addresses of areas 1 and 3 along with network masks of 24 cannot accommodate 500 users so are inadequate, while the area 2 is having over capacity so its network mask can be reduced to 25 to accommodate the only 60 users it has.

76. Given an IP address of 192.168.1.42 255.255.255.248, what is the subnet address?

  • 192.168.1.8/29
  • 192.168.1.32/27
  • 192.168.1.40/29
  • 192.168.1.16/28
  • 192.168.1.48/29

Explanation:

248 mask uses 5 bits (1111 1000)
42 IP in binary is (0010 1010)
The base subnet therefore is the lowest binary value that can be written without changing the output of an AND operation of the subnet mask and IP …
1111 1000 AND
0010 1010 equals
0010 1000 – which is 40/24 is standard class C mask, adding the 5 bits from the 248 mask gives /29

77. Which OSI layer header contains the address of a destination host that is on another network?

  • application
  • session
  • transport
  • network
  • data link
  • physical

Explanation: Only network address contains this information. To transmit the packets the sender uses network address and datalink address. But the layer 2 address represents just the address of the next hop device on the way to the sender. It is changed on each hop. Network address remains the same.

78. Which layer of the TCP/IP stack combines the OSI model physical and data link layers?

  • Internet layer
  • transport layer
  • application layer
  • network access layer

Explanation: The Internet Protocol Suite, TCP/IP, is a suite of protocols used for communication over the internet. The TCP/IP model was created after the OSI 7 layer model for two major reasons. First, the foundation of the Internet was built using the TCP/IP suite and through the spread of the World Wide Web and Internet, TCP/IP has been preferred. Second, a project researched by the Department of Defense (DOD) consisted of creating the TCP/IP protocols. The DOD’s goal was to bring international standards which could not be met by the OSI model. Since the DOD was the largest software consumer and they preferred the TCP/IP suite, most vendors used this model rather then the OSI. Below is a side by side comparison of the TCP/IP and OSI models. TCP/IP Model VS.
OSI Model Application Layer 7
Application
Layer 6
Presentation
Layer 5
Session Transport Layer 4
Transport Internet Layer 3
Network Network Access Layer 2
Data Link
Layer 1
Physical

79. Which protocol uses a connection-oriented service to deliver files between end systems?

  • TFTP
  • DNS
  • FTP
  • SNMP
  • RIP

Explanation: FTP is an acronym for File Transfer Protocol. As the name suggests, FTP is used to transfer files between computers on a network. You can use FTP to exchange files between computer accounts, transfer files between an account and a desktop computer, or access online software archives

80. Refer to the exhibit. If the hubs in the graphic were replaced by switches, what would be virtually eliminated?

  • broadcast domains
  • repeater domains
  • Ethernet collisions
  • signal amplification
  • Ethernet broadcasts

Explanation: Modern wired networks use a network switch to eliminate collisions. By connecting each device directly to a port on the switch, either each port on a switch becomes its own collision domain in the case of half duplex links) or the possibility of collisions is eliminated entirely in the case of full duplex links.

81. Refer to the exhibit. If host A sends an IP packet to host B, what will the source physical address be in the frame when it reaches host B?

  • 10.168.10.99
  • 10.168.11.88
  • A1:A1:A1:A1:A1:A1
  • B2:32:B2:B2:B2:32
  • C3.C3.C3.C3.C3.C3
  • D4:04:04:04:04:04

Explanation: When packets transfer from one host to another across a routed segment, the source IP address always remains the same source IP address, and the source physical (MAC) address will be the existing router’s interface address. Similarly, the destination IP address always remains the same and the destination physical (MAC) address is the destination router’s interface address.

82. Refer to the exhibit. Hostx is transferring a file to the FTP server. Point A represents the frame as it goes toward the Toronto router. What will the Layer 2 destination address be at this point?

  • abcd 1123.0045
  • 192.168.7.17
  • aabb.5555.2222
  • 192.168.1.1
  • abcd. 2246.0035

Explanation: For packets destined to a host on another IP network, the destination MAC address will be the LAN interface of the router. Since the FTP server lies on a different network, the host will know to send the frame to its default gateway, which is Toronto.

83. Which network device functions only at Layer 1 of the OSI model?

  • BRIDGE
  • HUB
  • NIC
  • ROUTER
  • SWITCH

Explanation: Most hubs are amplifying the electrical signal; therefore, they are really repeaters with several ports. Hubs and repeaters are Layer 1 (physical layer) devices.

84. Refer to the exhibit. The host in Kiev sends a request for an HTML document to the server in Minsk. What will be the source IP address of the packet as it leaves the Kiev router?

  • 10.1.0.1
  • 10.1.0.5
  • 10.1.0.6
  • 10.1.0.14
  • 10.1.1.16
  • 10.1.2.8

Explanation: Although the source and destination MAC address will change as a packet traverses a network, the source and destination IP address will not unless network address translation (NAT) is being done, which is not the case here.

85. Refer to the exhibit. As packets travel from Mary to Robert, which three devices will use the destination MAC address of the packet to determine a forwarding path? (Choose three.)

  • Hub1
  • Switch1
  • Router1
  • Switch2
  • Router2
  • Switch3

Explanation: Switches use the destination MAC address information for forwarding traffic, while routers use the destination IP address information. Local Area Networks employ Layer 2 Switches and Bridges to forward and filter network traffic. Switches and Bridges operate at the Data Link Layer of the Open System Interconnect Model (OSI). Since Switches and Bridges operate at the Layer 2 they operate more intelligently than hubs, which work at Layer 1 (Physical Layer) of the OSI. Because the switches and bridges are able to listen to the traffic on the wire to examine the source and destination MAC address. Being able to listen to the traffic also allows the switches and bridges to compile a MAC address table to better filter and forward network traffic. To accomplish the above functions switches and bridges carry out the following tasks:

MAC address learning by a switch or a bridge is accomplished by the same method. The switch or bridge listens to each device connected to each of its ports and scan the incoming frame for the source MAC address. This creates a MAC address to port map that is cataloged in the switches/ bridge MAC database. Another name for the MAC address table is content addressable memory orCAM table. When a switch or bridge is listening o the network traffic, it receives each frame and compares it to the MAC address table. By checking the MAC table the switch/ bridge are able o determine which port the frame came in on. If the frame is on the MAC table the frame is filtered or transmitted on only that port. If the switch determines that the frame is not on the MAC table, the frame is forwarded out to all ports except the incoming port.

86. Refer to the exhibit. Mary is sending an instant message to Robert. The message will be broken into a series of packets that will traverse all network devices. What addresses will populate these packets as they are forwarded from Router1 to Router2?

  • A
  • B
  • C
  • D
  • E

Explanation: The Source and Destination IP address is not going to change. Host 1 IP address will stay as being the source IP and the Host 2 IP address will stay the destination IP address. Those two are not going to change. For the MAC address it is going to change each time it goes from one hope to another. (Except switches… they don’t change anything) Frame leaving HOST 1 is going to have a source MAC of Host 1 and a destination MAC of Router1.

Router 1 is going to strip that info off and then will make the source MAC address of Router’s exiting interface, and making Router2’s interface as the destination MAC address. Then the same will happen… Router2 is going to change the source/destination info to the source MAC being the Router2 interface that it is going out, and the destination will be Host2’s MAC address

87. Refer to the exhibit. A network device needs to be installed in the place of the icon labeled Network Device to accommodate a leased line attachment to the Internet. Which network device and interface configuration meets the minimum requirements for this installation?

  • a router with two Ethernet interfaces
  • a switch with two Ethernet interfaces
  • a router with one Ethernet and one serial interface
  • a switch with one Ethernet and one serial interface
  • a router with one Ethernet and one modem interface

Explanation: Only a router can terminate a leased line attachment access circuit, and only a router can connect two different IP networks. Here, we will need a router with two interfaces, one serial connection for the line attachment and one Ethernet interface to connect to the switch on the LAN.

88. Which transport layer protocol provides best-effort delivery service with no acknowledgment receipt required?

  • HTTP
  • ІР
  • TCP
  • Telnet
  • UDP

Explanation: UDP provides a connectionless datagram service that offers best-effort delivery, which means that UDP does not guarantee delivery or verify sequencing for any datagrams. A source host that needs reliable communication must use either TCP or a program that provides its own sequencing and acknowledgment services.

89. Which layer of the OSI model controls the reliability of communications between network devices using flow control, sequencing and acknowledgments?

  • Physical
  • Data-link
  • Transport
  • Network

Explanation: There are many services that can be optionally provided by a transport-layer protocol, and different protocols may or may not implement them. Connection-oriented communication: It is normally easier for an application to interpret a connection as a data stream rather than having to deal with the underlying connection-less models, such as the datagram model of the User Datagram Protocol (UDP) and of the Internet Protocol (IP). Byte orientation:

Rather than processing the messages in the underlying communication system format, it is often easier for an application to process the data stream as a sequence of bytes. This simplification helps applications work with various underlying message formats. Same order delivery: The network layer doesn’t generally guarantee that packets of data will arrive in the same order that they were sent, but often this is a desirable feature. This is usually done through the use of segment numbering, with the receiver passing them to the application in order. This can cause head-of-line blocking. Reliability: Packets may be lost during transport due to network congestion and errors. By means of an error detection code, such as a checksum, the transport protocol may check that the data is not corrupted, and verify correct receipt by sending an ACK or NACK message to the sender. Automatic repeat request schemes may be used to retransmit lost or corrupted data.

Flow control: The rate of data transmission between two nodes must sometimes be managed to prevent a fast sender from transmitting more data than can be supported by the receiving data buffer, causing a buffer overrun. This can also be used to improve efficiency by reducing buffer underrun. Congestion avoidance: Congestion control can control traffic entry into a telecommunications network, so as to avoid congestive collapse by attempting to avoid oversubscription of any of the processing or link capabilities of the intermediate nodes and networks and taking resource reducing steps, such as reducing the rate of sending packets. For example, automatic repeat requests may keep the network in a congested state; this situation can be avoided by adding congestion avoidance to the flow control, including slow-start. This keeps the bandwidth consumption at a low level in the beginning of the transmission, or after packet retransmission. Multiplexing: Ports can provide multiple endpoints on a single node. For example, the name on a postal address is a kind of multiplexing, and distinguishes between different recipients of the same location. Computer applications will each listen for information on their own ports, which enables the use of more than one network service at the same time. It is part of the transport layer in the TCP/IP model, but of the session layer in the OSI model.

90. Hotspot Questions

Select two options which are security Issues which need to be modified before RouterA is used? (Choose two.)

  • unencrypted weak password is configured to protect privilege mode
  • inappropriate wording in banner message
  • the virtual terminal lines have a weak password configured
  • virtual terminal lines have a password, but it will not be used
  • configuration supports un-secure web server access

Explanation: This answer can be done by simulation only, don’t know user name password and banner message etc

91. Hotspot Questions

Select three options which are security issues with the current configuration of SwitchA. (Choose three.)

  • privilege mode is protected with an unencrypted password
  • inappropriate wording in banner message
  • virtual terminal lines are protected only by a password requirement
  • both the username and password are weak
  • telnet connections can be used to remotely manage the switch
  • cisco user will be granted privilege level 15 by default

Explanation: This answer can be done by simulation only, don’t know user name password and banner message etc

92. Hotspot Questions

Which two of the following are true regarding the configuration of RouterA? (Choose two.)

  • at least 5 simultaneous remote connections are possible
  • only telnet protocol connections to RouterA are supported
  • remote connections to RouterA using telnet will succeed
  • console line connections will nevertime out due to inactivity
  • since DHCP is not used on Fa0/1 there is not a need to use the NAT protocol

Explanation: The IP address can accommodate 5 hosts at least, telnet can be accessed on the router

93. Hotspot Questions

Which of the following is true regarding the configuration of SwitchA?

  • only 5 simultaneous remote connections are possible
  • remote connections using ssh will require a username and password
  • only connections from the local network will be possible
  • console access to SwitchA requires a password

Explanation: Ssh login requires a user name and password always while other conditions may or may not be true.

94. Refer to the output of the corporate router routing table shown in the graphic. The corporate router receives an IP packet with a source IP address of 192.168.214.20 and a destination address of 192.168.22.3. What will the router do with this packet?

  • It will encapsulate the packet as Frame Relay and forward it out interface Serial 0/0.117.
  • It will discard the packet and send an ICMP Destination Unreachable message out interface FastEthernet 0/0.
  • It will forward the packet out interface Serial 0/1 and send an ICMP Echo Reply message out interface serial 0/0.102.
  • It will change the IP packet to an ARP frame and forward it out FastEthernet 0/0.

95. An administrator must assign static IP addresses to the servers in a network. For network 192.168.20.24/29, the router is assigned the first usable host address while the sales server is given the last usable host address. Which of the following should be entered into the IP properties box for the sales server?

  • IP address: 192.168.20.14 Subnet Mask:255.255.255.248
    Default Gateway: 192.168.20.9
  • IP address: 192.168.20.254 Subnet Mask: 255.255.255.0
    Default Gateway: 192.168.20.1
  • IP address: 192.168.20.30 Subnet Mask: 255.255.255.248
    Default Gateway: 192.168.20.25
  • IP address: 192.168.20.30 Subnet Mask: 255.255.255.240
    Default Gateway: 192.168.20.17
  • IP address: 192.168.20.30 Subnet Mask: 255.255.255.240
    Default Gateway: 192.168.20.25

96. What is the default administrative distance of the OSPF routing protocol?

  • 90
  • 100
  • 110
  • 120
  • 130
  • 170

Explanation:

Default Distance Value Table
This table lists the administrative distance default values of the protocols that Cisco supports:

If the administrative distance is 255, the router does not believe the source of that route and does not install the route in the routing table.

97. What is the subnet address for the IP address 172.19.20.23/28?

  • 172.19.20.0
  • 172.19.20.15
  • 172.19.20.16
  • 172.19.20.20
  • 172.19.20.32

98. The network administrator has found the following problem. The remote networks 172.16.10.0, 172.16.20.0, and 172.16.30.0 are accessed through the Central router’s serial 0/0 interface. No users are able to access 172.16.20.0. After reviewing the command output shown in the graphic, what is the most likely cause of the problem?

  • no gateway of last resort on Central
  • Central router’s not receiving 172.16.20.0 update
  • incorrect static route for 172.16.20.0
  • 172.16.20.0 not located in Central’s routing table

99. Refer to the exhibit. The output is from a router in a large enterprise. From the output, determine the role of the router.

  • A Core router.
  • The HQ Internet gateway router.
  • The WAN router at the central site.
  • Remote stub router at a remote site.

100. Refer to the exhibit. For security reasons, information about RTA, including platform and IP addresses, should not be accessible from the Internet. This information should, however, be accessible to devices on the internal networks of RTA Which command or series of commands will accomplish these objectives?

  • RTA(config)#no cdp run
  • RTA(config)#no cdp enable
  • RTA(config)#interface s0/0 RTA(config-if)#no cdp run
  • RTA(config)#interface s0/O RTA(config-if)#no cdp enable

101. Refer to the exhibit. The two connected ports on the switch are not turning orange or green. What would be the most effective steps to troubleshoot this physical layer problem? (Choose three.)

  • Ensure that the Ethernet encapsulations match on the interconnected router and switch  ports.
  • Ensure that cables A and B are straight-through cables
  • Ensure cable A is plugged into a trunk port.
  • Ensure the switch has power.
  • Reboot all of the devices.
  • Reseat all cables.

102. Wich command can you use to manually assign a static IPv6 address to a router interface?

  • ipv6 address PREFIX_1.: 1/64
  • ipv6 autoconfig 2001 db8:2222:7272::72/64
  • ipv6 autoconfig
  • ipv6 address 2001:db8:2222:7272::72/64

103. The network administrator is using a Windows PC application that is called putty.exe for remote communication to a switch for network troubleshooting. Which two protocols could be used during this communication? (Choose two).

  • SNMP
  • HTTP
  • Telnet
  • RMON
  • SSH

104. What should be part of a comprehensive network security plan?

  • Allow users to develop their own approach to network security.
  • Physically secure network equipment from potential access by unauthorized individuals.
  • Encourage users to use personal information in their passwords to minimize the likelihood of passwords being forgotten.
  • Delay deployment of software patches and updates until their effect on end-user equipment is well known and widely reported.
  • Minimize network overhead by deactivating automatic antivirus client updates.

105. Which two of these statements are true of IPv6 address representation? (Choose two.)

  • There are four types of IPv6 addressesunicast, multicast, anycast, and broadcast.
  • A single interface may be assigned multiple IPv6 addresses of any type.
  • Every IPv6 interface contains at least one loopback address.
  • The first 64 bits represent the dynamically created interface ID.
  • Leading zeros in an IPv6 16 bit hexadecimal field are mandatory.

Explanation: http://www.cisco.com/en/US/technologies/tk648/tk872/technologies_white_paper0900aecd 8026003d.pdf

A single interface may be assigned multiple addresses of any type (unicast, anycast, multicast). Every IPv6-enabled interface must contain at least one loopback and one link-local address. Optionally, every interface can have multiple unique local and global addresses. IPv6 host addresses can be assigned in multiple ways:
Static configuration
Stateless autoconfiguration
DHCPv6
When IPv6 is used over Ethernet networks, the Ethernet MAC address can be used to generate the 64-bit interface ID for the host. This is called the EUI-64 address. Since MAC addresses use 48 bits, additional bits must be inserted to fill the 64 bits required.

106. A network administrator cannot connect to a remote router by using SSH. Part of the show interfaces command is shown.

router#show interfaces 
Serial0/1/0 is up, line protocol is down

At which OSI layer should the administrator begin troubleshooting?

  • physical
  • data link
  • network
  • transport

Explanation: https://learningnetwork.cisco.com/thread/12389

I think the indication here is “Serial O is up, line protocol is down”. What causes this indication? Correct me if I am wrong. When you have this indication, a cable unplugged is not a correct answer. If you check the output of your “show interface serial 0” command again, you should notice it as “Serial O is down, line protocol is down. Under the “show ip int brief” you should see status = down and protocol = down as opposed to up, down. Because you disconnected the cable, layer 1 will go down, which is indicated by the serial 0 down status. The line protocol status is for layer 2. So, a cable unplugged is not a correct answer to “Serial O is up, line protocol is down”. Hope this helps.

107. Refer to the exhibit. A person is trying to send a file from a host on Network A of the JAX Company to a server on Network Z of the XYZ Company. The file transfer fails. The host on Network A can communicate with other hosts on Network A. Which command, issued from router RTA, would be the most useful for troubleshooting this problem?

  • show flash:
  • show history
  • show version
  • show interfaces
  • show controllers serial

108. Refer to the exhibit. A user cannot reach any web sites on the Internet, but others in the department are not having a problem. What is the most likely cause of the problem?

  • IP routing is not enabled.
  • The default gateway is not in the same subnet.
  • A DNS server address is not reachable by the PC.
  • A DHCP server address is not reachable by the PC.
  • NAT has not been configured on the router that connects to the Internet.

109. Which option is a valid IPv6 address?

  • 2001:0000:130F::099a::12a
  • 2002:7654:A1AD:61:81AF:CCC1
  • FEC0:ABCD:WXYZ:0067::2A4
  • 2004:1:25A4:886F::1

Explanation:

http://www.ipv6.com/articles/general/IPv6-Addressing.htm
IPv6 Address Notation
IPv6 addresses are denoted by eight groups of hexadecimal quartets separated by colons in between them.
Following is an example of a valid IPv6 address:
2001.cdba: 0000:0000-0000:0000:3257:9652
Any four-digit group of zeroes within an IPv6 address may be reduced to a single zero or altogether omitted.
Therefore, the following IPv6 addresses are similar and equally valid:
2001.cdba:0000:0000:0000:0000:3257:9652
2001:cdba:0:0:0:0:3257:9652
2001.cdba: 3257:9652
The URL for the above address will be of the form:
http:// [2001.cdba:0000:0000-0000:0000:3257:9652]/

110. What is the purpose of the switchport command?

Switch(config-if)# switchport port-security maximum 1 
Switch(config-if)# switchport port-security mac-address 0018.DE8B.4BF8
  • It ensures that only the device with the MAC address 0018.DE8B.4BF8 will be able to connect to the port that is being configured.
  • It informs the switch that traffic destined for MAC address 0018.DE8B.4BF8 should only be sent to the port that is being configured.
  • It will act like an access list and the port will filter packets that have a source or destination MAC of 0018.DE8B.4BF8.
  • The switch will shut down the port of any traffic with source MAC address of
    0018.DE8B.4BF8.

111. Refer to the exhibit. A network administrator is troubleshooting a connectivity problem on the serial interfaces. The output from the show interfaces command on both routers shows that the serial interface is up, line protocol is down. Given the partial output for the show running-config in the exhibit, what is the most likely cause of this problem?

  • The serial cable is bad.
  • The MTU is incorrectly configured.
  • The Layer 2 framing is misconfigured.
  • The IP addresses are not in the same subnet.

112. How many bits are contained in each field of an IPv6 address?

  • 24
  • 4
  • 8
  • 16

Explanation: http://www.cisco.com/en/US/technologies/tk648/tk872/ technologies_white_paper0900aecd 8026003d.pdf

One of the key advantages IPv6 brings is the exponentially larger address space. The following will outline the basic address architecture of IPv6.
128-bit-long addresses
Represented in hexadecimal format: Uses CIDR principles prefix/prefix length X.XXX.XXXX, where x is a 16-bit hex field The last 64 bits are used for the interface ID

113. Refer to the exhibit. The DHCP settings have recently been changed on the DHCP server and the client is no longer able to reach network resources. What should be done to correct this situation?

  • Verify that the DNS server address is correct in the DHCP pool.
  • Ping the default gateway to populate the ARP cache
  • Use the tracert command on the DHCP Client to first determine where the problem is located
  • Clear all DHCP leases on the router to prevent address conflicts.
  • Issue the ipconfig command with the /release and /renew options in a command window

114. Which three approaches can be used while migrating from an IPv4 addressing scheme to an IPv6 scheme (choose three)

  • static mapping of IPv4 address to IPv6 addresses
  • configuring IPv4 tunnels between IPv6 islands
  • use DHCPv6 to map IPv4 addresses to IPv6 addresses
  • use proxying and translation (NAT-PT) to translate IPv6 packets into IPv4 packets
  • configure IPv6 directly
  • enable dual-stack routing

Explanation: http://www.opus1.com/ipv6/howdoitransitiontoipv6.html
Connecting IPv6 islands with tunnels
An IPv6 island is a network made of IPv6 links directly connected by IPv6 routers. In the early days of IPv6 deployment, there are many IPv6 islands. IPv6 in IPv4 tunnels are used to connect those islands together. In each island, one (or more) dual stack routers are designated to encapsulate and decapsulate IPv6 packets within IPv4 packets. Different mechanisms have been developed to manage tunnels: automatic tunnels3, configured tunnels3, tunnel brokers3, 6over43, 6to43,… http://www.petri.co.il/ipv6-transition.htm
Network Address Translation – Protocol Translation (NAT-PT) The NAT-PT method enables the ability to either statically or dynamically configure a translation of a IPv4 network address into an IPv6 network address and vice versa. For those familiar with more typically NAT implementations, the operation is very similar but includes a protocol translation function. NAT-PT also ties in an Application Layer Gateway (ALG) functionality that converts Domain Name System (DNS) mappings between protocols.
Dual Stack
The simplest approach when transitioning to IPv6 is to run IPv6 on all of the devices that are currently running IPv4. If this is something that is possible within the organizational network, it is very easy to implement.
However, for many organizations, IPv6 is not supported on all of the IPv4 devices, in these situations other methods must be considered.

115. Refer to the exhibit. A network technician is asked to design a small network with redundancy. The exhibit represents this design, with all hosts configured in the same VLAN. What conclusions can be made about this design?

  • This design will function as intended.
  • Spanning-tree will need to be used.
  • The router will not accept the addressing scheme.
  • The connection between switches should be a trunk.
  • The router interfaces must be encapsulated with the 802.1Q protocol.

116. Refer to the exhibit. An administrator replaced the 10/100 Mb NIC in a desktop PC with a 1 Gb NIC and now the PC will not connect to the network. The administrator began troubleshooting on the switch. Using the switch output shown, what is the cause of the problem?

  • Speed is set to 100Mb/s.
  • Input flow control is off.
  • Encapsulation is set to ARPA.
  • The port is administratively down.
  • The counters have never been cleared.

117. Refer to the exhibit. A technician is troubleshooting a host connectivity problem. The host is unable to ping a server connected to Switch_A. Based on the results of the testing, what could be the problem?

  • A remote physical layer problem exists.
  • The host NIC is not functioning.
  • TCP/IP has not been correctly installed on the host.
  • A local physical layer problem exists.

118. Which statement about IPv6 is true?

  • Addresses are not hierarchical and are assigned at random.
  • Only one IPv6 address can exist on a given interface.
  • There are 2.7 billion addresses available.
  • Broadcasts have been eliminated and replaced with multicasts.

Explanation: http://technet.microsoft.com/en-us/library/cc757359(v=ws. 10).aspx
IPv6 has three types of addresses, which can be categorized by type and scope:
Unicast addresses. A packet is delivered to one interface.
Multicast addresses. A packet is delivered to multiple interfaces.
Anycast addresses. A packet is delivered to the nearest of multiple interfaces (in terms of routing distance)
IPv6 does not use broadcast messages.
Unicast and anycast addresses in IPv6 have the following scopes (for multicast addresses, the scope are built into the address structure):
Link-local. The scope is the local link (nodes on the same subnet). Site-local. The scope is the organization (private site addressing). Global. The scope is global (IPv6 Internet addresses). In addition, IPv6 has special addresses such as the loopback address. The scope of a special address depends on the type of special address.
Much of the IPv6 address space is unassigned.

119. What are two recommended ways of protecting network device configuration files from outside network security threats? (Choose two.)

  • Allow unrestricted access to the console or VTY ports.
  • Use a firewall to restrict access from the outside to the network devices.
  • Always use Telnet to access the device command line because its data is automatically encrypted.
  • Use SSH or another encrypted and authenticated transport to access device configurations.
  • Prevent the loss of passwords by disabling password encryption.

120. Refer to the exhibit. A problem with network connectivity has been observed. It is suspected that the cable connected to switch port Fa0/9 on Switch1 is disconnected. What would be an effect of this cable being disconnected?

  • Host B would not be able to access the server in VLANS until the cable is reconnected.
  • Communication between VLAN3 and the other VLANs would be disabled.
  • The transfer of files from Host B to the server in VLANS would be significantly slower.
  • For less than a minute, Host B would not be able to access the server in VLAN9. Then normal network function would resume.

121. A receiving host has failed to receive all of the segments that it should acknowledge. What can the host do to improve the reliability of this communication session?

  • decrease the window size
  • use a different source port for the session
  • decrease the sequence number
  • obtain a new IP address from the DHCP server
  • start a new session using UDP

122. Which command enables IPv6 forwarding on a cisco router?

  • ipv6 host
  • ipv6 unicast-routing
  • ipv6 local
  • ipv6 neighbor

Explanation: Enabling IPv6 on Cisco IOS Software Technology http://www.ciscopress.com/articles/article.asp?p=31948&seqNum=4
The first step of enabling IPv6 on a Cisco router is the activation of IPv6 traffic forwarding to forward unicast IPv6 packets between network interfaces. By default, IPv6 traffic forwarding is disabled on Cisco routers.
The ipv6 unicast-routing command is used to enable the forwarding of IPv6 packets between interfaces on the router. The syntax for this command is as follows: Router(config)#ipv6 unicast-routing
The ipv6 unicast-routing command is enabled on a global basis.

123. Refer to the exhibit. A host is connected to switch port fa0/3. The host and switch have been fully configured for IP connectivity as shown. However, the indicator LED on switch port fa0/3 is not on, and the host cannot communicate with any other hosts including those connected to VLAN 2 on the same switch. Based on the given information, what is the problem?

  • switch port fa0/3 is not configured as a trunk port
  • there is a bad cable
  • the switch has been assigned an incorrect subnet mask
  • switch port fa0/3 has been blocked by STP
  • the switch and the host must be in the same subnet

124. Identify the four valid IPv6 addresses. (Choose four.)

  • ::
  • ::192:168:0:1
  • 2000::
  • 2001:3452:4952:2837::
  • 2002:c0a8:101::42
  • 2003:dead:beef:4dad:23:46:bb:101

Explanation:

http://www.intermapper.com/ipv6validator
http://www.ripe.net/lir-services/new-lir/ipv6_reference_card.pdf

125. Which two statements describe characteristics of IPv6 unicast addressing? (Choose two.)

  • Global addresses start with 2000:/3.
  • Link-local addresses start with FE00:/12.
  • Link-local addresses start with FF00:/10.
  • There is only one loopback address and it is ::1.
  • If a global address is assigned to an interface, then that is the only allowable address for the interface.

126. A network administrator is trying to add a new router into an established OSPF network. The networks attached to the new router do not appear in the routing tables of the other OSPF routers Given the information in the partial configuration shown below, what configuration error is causing this problem?

Router (config)# router ospf 1 
Router (config-router) # network 10.0.0.0 255.0.0.0 area 0
  • The process id is configured improperly.
  • The OSPF area is configured improperly.
  • The network wildcard mask is configured improperly.
  • The network number is configured improperly.
  • The AS is configured improperly.
  • The network subnet mask is configured improperly.

Explanation:

When configuring OSPF, the mask used for the network statement is a wildcard mask similar to an access list. In this specific example, the correct syntax would have been “network 10.0.0.0 0.0.0.255 area 0.”

127. Which statement is true?

  • An IPv6 address is 64 b long and is represented as hexadecimal characters.
  • An IPv6 address is 32 b long and is represented as decimal digits.
  • An IPv6 address is 128 b long and is represented as decimal digits.
  • An IPv6 address is 128 b long and is represented as hexadecimal characters.

128. To allow or prevent load balancing to network 172.16.3.0/24, which of the following commands could be used in R2? (Choose two.)

  • R2(config-if)#clock rate
  • R2(config-if)#bandwidth
  • R2(config-if)#ip ospf cost
  • R2(config-if)#ip ospf priority
  • R2(config-router)#distance ospf

Explanation:

http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a00800949e.sht ml#t6 The cost (also called metric) of an interface in OSPF is an indication of the overhead required to send packets across a certain interface. The cost of an interface is inversely proportional to the bandwidth of that interface. A higher bandwidth indicates a lower cost. There is more overhead (higher cost) and time delays involved in crossing a 56k serial line than crossing a 10M Ethernet line. The formula used to calculate the cost is:
Cost = 10000 0000/bandwidth in bps
For example, it will cost 10 EXP8/10 EXP7 = 10 to cross a 10M Ethernet line and will cost 10 EXP8/1544000 =64 to cross a T1 line.
By default, the cost of an interface is calculated based on the bandwidth; you can force the cost of an interface with the ip ospf cost <value> interface subconfiguration mode command.

129. After the network has converged, what type of messaging, if any, occurs between R3 and R4?

  • No messages are exchanged
  • Hellos are sent every 10 seconds.
  • The full database from each router is sent every 30 seconds.
  • The routing table from each router is sent every 60 seconds.

Explanation: HELLO messages are used to maintain adjacent neighbors so even when the network is converged, hellos are still exchanged. On broadcast and point-to-point links, the default is 10 seconds, on NBMA the default is 30 seconds.

Although OSPF is a link-state protocol but the full database from each router is sent every 30 minutes (not seconds) -> C and D are not correct.

130. OSPF is configured using default classful addressing. With all routers and interfaces operational, how many networks will be in the routing table of R1 that are indicated to be learned by OSPF?

  • 2
  • 3
  • 4
  • 5
  • 6
  • 7

131. R1 is configured with the default configuration of OSPF. From the following list of IP addresses configured on R1, which address will the OSPF process select as the router ID?

  • 192.168.0.1
  • 172.16.1.1
  • 172.16.2.1
  • 172.16.2.225

Explanation: The Router ID (RID) is an IP address used to identify the router and is chosen using the following sequence:
+ The highest IP address assigned to a loopback (logical) interface.
+ If a loopback interface is not defined, the highest IP address of all active router’s physical interfaces will be chosen.
+ The router ID can be manually assigned
In this case, because a loopback interface is not configured so the highest active IP address 192.168.0.1 is chosen as the router ID.

132. R1 is unable to establish an OSPF neighbor relationship with R3. What are possible reasons for this problem? (Choose two)

  • All of the routers need to be configured for backbone Area 1.
  • R1 and R2 are the DR and BDR, SO OSPF will not establish neighbor adjacency with R3.
  • A static route has been configured from R1 to R3 and prevents the neighbor adjacency from being established
  • The hello and dead interval timers are not set to the same values on R1 and R3.
  • EIGRP is also configured on these routers with a lower administrative distance.
  • R1 and R3 are configured in different areas.

Explanation:

To become OSPF neighbors, routers must meet these requirements: Hello interval, Dead interval and AREA number -> D and F are correct.

133. What information does a router running a link-state protocol use to build and maintain its topological database? (Choose two)

  • hello packets
  • SAP messages sent by other routers
  • LSAs from other routers
  • beacons received on point-to-point links
  • routing tables received from other link-state routers
  • TTL packets from designated routers

134. 

ROUTER# show ip route
192.168.12.0/24 is variably subnetted, 9 subnets, 3 masks 
C 192.168.12.64 28 is directly connected, Loopback1 
C 192.168.12.32 28 is directly connected, Etherneto 
C 192.168.12.48 /28 is directly connected, Loopbacko 
O 192.168.12.236 /30 (110/128] via 192.168.12.233, 00:35:36, Serialo C 192.168.12.232 /30 is directly connected, Serialo 
O 192.168.12.245/30 (110/782] via 192.168.12.233, 00:35:36, Serialo 
O 192.168.12.240 /30 [110/128] via 192.168.12.233, 00:35:36, Serialo 
O 192.168.12.253/30 (110/782] via 192.168.12.233, 00:35:37, Serialo 
O 192.168.12.249 /30 (110/782] via 192.168.12.233, 00:35:37, Serialo 
O 192.168.12.240/30 (110/128] via 192.168.12.233, 00:35:36, Serial O

To what does the 128 refer to in the router output above?

  • OSPF cost
  • OSPF priority
  • OSPF hop count
  • OSPF ID number
  • OSPF administrative distance

Explanation: The first parameter is the Administrative Distance of OSPF (110) while the second parameter is the cost of OSPF.

135. Which of the following describe the process identifier that is used to run OSPF on a router? (Choose two)

  • It is locally significant.
  • It is globally significant.
  • It is needed to identify a unique instance of an OSPF database.
  • It is an optional parameter required only if multiple OSPF processes are running on the router.
  • All routers in the same OSPF area must have the same process ID if they are to exchange routing information.

Explanation: https://learningnetwork.cisco.com/thread/6248
They are locally significant only, and have no bearing on the structure of any OSPF packet or LSA update. So you can have a separate process-id on every single router in your network if you so desire!

136. Open Shortest Path First (OSPF) is a routing protocol developed for Internet Protocol (IP) networks by the Interior Gateway Protocol (IGP) working group of the Internet Engineering Task Force (IETF). What is the default administrative distance of the OSPF routing protocol?

  • 90
  • 100
  • 110
  • 20
  • 130
  • 170

137. The internetwork infrastructure of company XYZ consists of a single OSPF area as shown in the graphic. There is concern that a lack of router resources is impeding internetwork performance. As part of examining the router resources, the OSPF DRs need to be known. All the router OSPF priorities are at the default and the router IDs are shown with each router. Which routers are likely to have been elected as DR? (Choose two.)

  • Corp-1
  • Corp-2
  • Corp-3
  • Corp-4
  • Branch-1
  • Branch-2

Explanation: There are 2 segments on the topology above which are separated by Corp-3 router. Each segment will have a DR so we have 2 DRs.

To select which router will become DR they will compare their router-IDs. The router with highest (best) router-ID will become DR. The router-ID is chosen in the order below:
+ The highest IP address assigned to a loopback (logical) interface.
+ If a loopback interface is not defined, the highest IP address of all active router’s physical interfaces will be chosen.

In this question, the IP addresses of loopback interfaces are not mentioned so we will consider IP addresses of all active router’s physical interfaces. Router Corp-4 (10.1.40.40) & Branch-2 (10.2.20.20) have highest “active” IP addresses so they will become DRs.

138. Which address are OSPF hello packets addressed to on point-to-point networks?

  • 224.0.0.5
  • 172.16.0.1
  • 192.168.0.5
  • 223.0.0.1
  • 254.255.255.255

Explanation: Why Does the show ip ospf neighbor Command Reveal Neighbors in the Init State?
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f11.shtml
OSPF hello packets have a destination address of 224.0.0.5 (the all ospf routers multicast address).

139. Which statements describe the routing protocol OSPF? (Choose three)

  • It supports VLSM.
  • It is used to route between autonomous systems.
  • It confines network instability to one area of the network.
  • It increases routing overhead on the network
  • It allows extensive control of routing updates.
  • It is simpler to configure than RIP v2.

Explanation: The OSPF protocol is based on link-state technology, which is a departure from the Bellman-Ford vector based algorithms used in traditional Internet routing protocols such as RIP. OSPF has introduced new concepts such as authentication of routing updates, Variable Length Subnet Masks (VLSM), route summarization, and so forth.

OSPF uses flooding to exchange link-state updates between routers. Any change in routing information is flooded to all routers in the network. Areas are introduced to put a boundary on the explosion of link-state updates. Flooding and calculation of the Dijkstra algorithm on a router is limited to changes within an area.

140. Refer to the graphic. R1 is unable to establish an OSPF neighbor relationship with R3. What are possible reasons for this problem? (Choose two)

  • All of the routers need to be configured for backbone Area 1
  • R1 and R2 are the DR and BDR, SO OSPF will not establish neighbor adjacency with R3
  • A static route has been configured from R1 to R3 and prevents the neighbor adjacency from being established
  • The hello and dead interval timers are not set to the same values on R1 and R3
  • EIGRP is also configured on these routers with a lower administrative distance
  • R1 and R3 are configured in different areas

Explanation: This question is to examine the conditions for OSPF to create neighborhood. So as to make the two routers become neighbors, each router must be matched with the following items:

1. The area ID and its types;
2. Hello and failure time interval timer,
3.OSPF Password (Optional);

141. Given the output for this command, if the router ID has not been manually set, what router ID will OSPF use for this router?

  • 10.1.1.2
  • 10.154.154.1
  • 172.16.5.1
  • 192.168.5.3

Explanation: The highest IP address of all loopback interfaces will be chosen -> Loopback O will be chosen as the router ID

142. Which parameter or parameters are used to calculate OSPF cost in Cisco routers?

  • Bandwidth
  • Bandwidth and Delay
  • Bandwidth, Delay, and MTU
  • Bandwidth, MTU, Reliability, Delay, and Load

Explanation: The well-known formula to calculate OSPF cost is Cost = 108 / Bandwidth

143. Why do large OSPF networks use a hierarchical design? (Choose three.)

  • to decrease latency by increasing bandwidth
  • to reduce routing overhead
  • to speed up convergence
  • to confine network instability to single areas of the network
  • to reduce the complexity of router configuration
  • to lower costs by replacing routers with distribution layer switches

Explanation: OSPF implements a two-tier hierarchical routing model that uses a core or backbone tier known as area zero (O). Attached to that backbone via area border routers (ABRs) are a number of secondary tier areas. The hierarchical approach is used to achieve the following:

-Rapid convergence because of link and/or switch failures

-Deterministic traffic recovery – Scalable and manageable routing hierarchy, reduced routing overhead.

144. Refer to the exhibit. When running OSPF, what would cause router A not to form an adjacency with router B?

  • The loopback addresses are on different subnets.
  • The values of the dead timers on the routers are different.
  • Route summarization is enabled on both routers.
  • The process identifier on router A is different than the process identifier on router B.

Explanation: To form an adjacency (become neighbor), router A & B must have the same Hello interval, Dead interval and AREA numbers

145. A router has learned three possible routes that could be used to reach a destination network. One route is from EIGRP and has a composite metric of 20514560. Another route is from OSPF with a metric of 782. The last is from RIPv2 and has a metric of 4. Which route or routes will the router install in the routing table?

  • the OSPF route
  • the EIGRP route
  • the RIPv2 route
  • all three routes
  • the OSPF and RIPv2 routes

Explanation: When one route is advertised by more than one routing protocol, the router will choose to use the routing protocol which has lowest Administrative Distance. The Administrative Distances of popular routing protocols are listed below:

146. Which command is used to display the collection of OSPF link states?

  • show ip ospf link-state
  • show ip ospf Isa database
  • show ip ospf neighbors
  • show ip ospf database

Explanation:

The “show ip ospf database” command displays the link states. Here is an example: Here is the Isa database on R2.

147. Refer to the exhibit. A network associate has configured OSPF with the command:

City (config-router) # network 192.168.12.64 0.0.0.63 area o

After completing the configuration, the associate discovers that not all the interfaces are participating in OSPF. Which three of the interfaces shown in the exhibit will participate in OSPF according to this configuration statement? (Choose three.)

  • FastEthernet0/0
  • FastEthernet0/1
  • Serial0/0
  • Serial0/1.102
  • Serial0/1.103
  • Serial0/1.104

Explanation: The “network 192.168.12.64 0.0.0.63 equals to network 192.168.12.64/26. This network has: + Increment: 64 (126= 1111 1111.1111 1111.1111 1111.1100 0000) + Network address: 192.168.12.64

+ Broadcast address: 192.168.12.127

Therefore all interface in the range of this network will join OSPF.

148. What is the default administrative distance of OSPF?

  • 90
  • 100
  • 110
  • 120

Explanation: Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value.

Default Distance Value Table

This table lists the administrative distance default values of the protocols that Cisco supports:

149. Which two statements describe the process identifier that is used in the command to configure OSPF on a router? (Choose two.)

Router (config)# router ospf 1
  • All OSPF routers in an area must have the same process ID.
  • Only one process number can be used on the same router.
  • Different process identifiers can be used to run multiple OSPF processes
  • The process number can be any number from 1 to 65,535.
  • Hello packets are sent to each neighbor to determine the processor identifier.

Explanation: Multiple OSPF processes can be configured on a router using multiple process ID’s. The valid process ID’s are shown below:

Edge-B(config)#router ospf ?
<1-65535> Process ID

150. Which commands are required to properly configure a router to run OSPF and to add network 192.168.16.0/24 to OSPF area 0? (Choose two.)

  • Router(config)# router ospf 0
  • Router(config)# router ospf 1
  • Router(config)# router ospf area 0
  • Router(config-router)# network 192.168.16.0 0.0.0.255 0
  • Router(config-router)# network 192.168.16.0 0.0.0.255 area 0
  • Router(config-router)# network 192.168.16.0 255.255.255.0 area 0

Explanation: In the router ospf command, the ranges from 1 to 65535 so o is an invalid number -> but To configure OSPF, we need a wildcard in the “network” statement, not a subnet mask. We also need to assgin an area to this process ->.

151. What is the default maximum number of equal-cost paths that can be placed into the routing table of a Cisco OSPF router?

  • 2
  • 8
  • 16
  • unlimited

Explanation:

maximum-paths (OSPF)
To control the maximum number of parallel routes that Open Shortest Path First (OSPF) can support, use the maximum-paths command.
Syntax Description

Command Default
8 paths

152. A network administrator is troubleshooting the OSPF configuration of routers R1 and R2. The routers cannot establish an adjacency relationship on their common Ethernet link.

The graphic shows the output of the show ip ospf interface el command for routers R1 and R2 Based on the information in the graphic, what is the cause of this problem?

  • The OSPF area is not configured properly.
  • The priority on R1 should be set higher.
  • The cost on R1 should be set higher.
  • The hello and dead timers are not configured properly.
  • A backup designated router needs to be added to the network.
  • The OSPF process ID numbers must match.

Explanation: In OSPF, the hello and dead intervals must match and here we can see the hello interval is set to 5 on R1 and 10 on R2. The dead interval is also set to 20 on R1 but it is 40 on R2.

153. OSPF routing uses the concept of areas. What are the characteristics of OSPF areas? (Choose Three.)

  • Each OSPF area requires a loopback interface to be configured.
  • Areas may be assigned any number from 0 to 65535.
  • Area 0 is called the backbone area.
  • Hierarchical OSPF networks do not require multiple areas.
  • Multiple OSPF areas must connect to area 0.
  • Single area OSPF networks must be configured in area 1.

Explanation: Definition of OSPF areas: An OSPF network may be structured, or subdivided into routing areas to simplify administration and optimize traffic and resource utilization. Areas are identified by 32bit numbers, expressed either simply in decimal, or often in octet-based dot-decimal notation, familiar from IPv4 address notation.

See discussion following Cisco Learning discussion. https://learningnetwork.cisco.com/ message/90832

154. Refer to the exhibit. Assume that all router interfaces are operational and correctly configured. In addition, assume that OSPF has been correctly configured on router R2. How will the default route configured on R1 affect the operation of R2?

  • Any packet destined for a network that is not directly connected to router R2 will be dropped immediately.
  • Any packet destined for a network that is not referenced in the routing table of router R2 will be directed to R1. R1 will then send that packet back to R2 and a routing loop will occur.
  • Any packet destined for a network that is not directly connected to router R1 will be dropped.
  • The networks directly connected to router R2 will not be able to communicate with the 172.16.100.0, 172.16.100.128, and 172.16.100.64 subnetworks.
  • Any packet destined for a network that is not directly connected to router R2 will be dropped immediately because of the lack of a gateway on R1.

Explanation: First, notice that the more-specific routes will always be favored over less-specific routes regardless of the administrative distance set for a protocol. In this case, because we use OSPF for three networks (172.16.100.0 0.0.0.3, 172.16.100.64 0.0.0.63, 172.16.100.128 0.0.0.31) so the packets destined for these networks will not be affected by the default route. The default route configured on R1 “ip route 0.0.0.0 0.0.0.0 serial0/0 will send any packet whose destination network is not referenced in the routing table of router R1 to R2, it doesn’t drop anything. These routes are declared in R1 and the question-says that “OSPF has been correctly configured on router R2, so network directly connected to router R2 can communicate with those three subnetworks. As said above, the default route configured on R1 will send any packet destined for a network that is not referenced in its routing table to R2, R2 in turn sends it to R1 because it is the only way and a routing loop will occur.

155. Refer to the exhibit. Which two statements are true about the loopback address that is configured on RouterB? (Choose two.)

  • It ensures that data will be forwarded by RouterB.
  • It provides stability for the OSPF process on RouterB.
  • It specifies that the router ID for RouterB should be 10.0.0.1.
  • It decreases the metric for routes that are advertised from RouterB.
  • It indicates that RouterB should be elected the DR for the LAN.

Explanation: A loopback interface never comes down even if the link is broken so it provides stability for the OSPF process (for example we use that loopback interface as the router-id) – The router-ID is chosen in the order below:

+ The highest IP address assigned to a loopback (logical) interface.

+ If a loopback interface is not defined, the highest IP address of all active router’s physical interfaces will be chosen. -> The loopback interface will be chosen as the router ID of RouterB –

156. Which characteristics are representative of a link-state routing protocol? (Choose three.)

  • provides common view of entire topology
  • exchanges routing tables with neighbors
  • calculates shortest path
  • utilizes event-triggered updates
  • utilizes frequent periodic updates

Explanation: Each of routers running link-state routing protocol learns paths to all the destinations in its “area” so we can say although it is a bit unclear.

Link-state routing protocols generate routing updates only (not the whole routing table) when a change occurs in the network topology so Link-state routing protocol like OSPF uses Dijkstra algorithm to calculate the shortest path >. Unlike Distance vector routing protocol (which utilizes frequent periodic updates), link-state routing protocol utilizes event-triggered updates (only sends update when a change occurs)->

157. Refer to the exhibit. The network is converged. After link-state advertisements are received from Router_A, what information will Router_E contain in its routing table for the subnets 208.149.23.64 and 208.149.23.96?

  • 208.149.23.64[110/13] via 190.173.23.10, 00:00:07, FastEthemet0/0
    208.149.23.96[110/13] via 190.173.23.10, 00:00:16, FastEthemet0/0
  • 208.149.23.64[110/1] via 190.172.23.10, 00:00:07, Serial1/0
    208.149.23.96[110/3] via 190.173.23.10, 00:00:16, FastEthemet0/0
  • 208.149.23.64[110/13] via 190.173.23.10, 00:00:07, Serial1/0
    208.149.23.96[110/13] via 190.173.23.10, 00:00:16, Serial1/0
    208.149.23.96[110/13] via 190.173.23.10, 00:00:16, FastEthemet0/0
  • 208.149.23.64[110/3] via 190.172.23.10, 00:00:07, Serial1/0
    208.149.23.96[110/3] via 190.173.23.10, 00:00:16, Serial1/0

Explanation: Router_E learns two subnets subnets 208.149.23.64 and 208.149.23.96 via Router_A through FastEthernet interface. The interface cost is calculated with the formula 108 / Bandwidth. For FastEthernet it is 108/100 Mbps = 108/100,000,000 = 1. Therefore the cost is 12 (learned from Router_A) + 1 = 13 for both subnets-> The cost through T1 link is much higher than through T3 link (T1 cost = 108 /1.544 Mbps = 64; T3 cost = 108 / 45 Mbps = 2) so surely OSPF will choose the path through T3 link -> Router_E will choose the path from Router_A through FastEthernet0/0, not Serial1/0. In fact, we can quickly eliminate answers B, C and D because they contain at least one subnet learned from Serial 1/0 -> they are surely incorrect.

158. What information can be used by a router running a link-state protocol to build and maintain its topological database? (Choose two.)

  • hello packets
  • SAP messages sent by other routers
  • LSAs from other routers
  • beacons received on point-to-point links
  • routing tables received from other link-state routers
  • TTL packets from designated routers

159. Lab Simulation – CLI Configuration

Attention:

In practical examinations, please note the following, the actual information will prevail.

1.Name of the router is xxx
2.Enable. secret password is xxx
3.Password In access user EXEC mode using the console is xxx
4. The password to allow telnet access to the router is xxx
5.IP information

Answer: [None]

ANSWER:

Router>enable
Router#config terminal
Router(config)#hostname Gotha
Gotha(config)#enable secret mi222ke
Gotha(config)#line console 0
Gotha(config-line)#password G8tors1
Gotha(config-line #exit
Gotha(config)#line vty 0 4
Gotha(config-line)#password dun63lap
Gotha(config-line)#login
Gotha(config-line)#exit
Gotha(config)#interface fa0/0
Gotha(config-if)#no shutdown
Gotha(config-if)#ip address 209.165.201.4 255.255.255.224
Gotha(config)#interface s0/0/0
Gotha(config-if)#ip address 192.0.2.190 255.255.255.240
Gotha(config-if)#no shutdown
Gotha(config-if)#exit
Gotha(config)#router rip
Gotha(config-router)#version 2
Gotha(config-router)#network 209.165.201.0
Gotha(config-router)#network 192.0.2.176
Gotha(config-router)#end
Gotha#copy run start

160. Lab Simulation – OSPF

Answer: [None]

Answer:

The question-mentioned Boston router was not configured correctly or incomplete so we should check this router first. Click on PC-B to access the command line interface (CLI) of Boston router.

Boston>enable (type cisco as its password here)
Boston#show running-config

First, remember that the current OSPF Process ID is 2 because we will need it for later configuration. Next notice that in the second “network” command the network and wildcard mask are 192.168.155.0 and 0.0.0.3 which is equivalent to 192.168.155.0 255.255.255.252 in term of subnet mask. Therefore this subnetwork’s range is from 192.168.155.0 to 192.168.155.3 but the ip address of s0/0 interface of Boston router is 192.168.155.5 which don’t belong to this range -> this is the reason why OSPF did not recognize so interface of Boston router as a part of area 0. So we need to find a subnetwork that so interface belongs to.

IP address of SO interface: 192.168.155.5/30

Subnet mask: /30 = 1111 1111.1111 1111.1111 1111.1111 1100

Increment: 4

Network address (which IP address of so interface belongs to):

192.168.155.4 (because 4* 1 = 4 <5)

Therefore we must use this network instead of 192.168.155.0 network

Boston#configure terminal 
Boston (config)#router ospf 2 
Boston (config-router) no network 192.168.155.0 0.0.0.3 area 0 
Boston (config-router) #network 192.168.155.4 0.0.0.3 area 0 
Boston (config-router) #end 
Boston#copy running-config startup-config

Finally, you should issue a ping command from Boston router to Lancaster router to make sure it works well.

Boston#ping 192.168.43.1

161. This topology contains 3 routers and 1 switch Complete the topology.

Drag the appropriate device icons to the labeled Device
Drag the appropriate connections to the locations labeled Connections Drag the appropriate IP addresses to the locations labeled IP address

(Hintuse the given host addresses and Main router information)
To remove a device or connection, drag it away from the topology.
Use information gathered from the Main router to complete the configuration of any additional routers. No passwords are required to access the Main router. The config terminal command has been disabled for the HQ router. The router does not require any configuration
Configure each additional router with the following:

Configure the interfaces with the correct IP address and enable the interfaces.
Set the password to allow console access to consolepw
Set the password to allow telnet access to telnetpw
Set the password to allow privilege mode access to privpw

Note: Because routes are not being added to the configurations, you will not be able to ping through the internetwork.
All devices have cable autosensing capabilities disabled.
All hosts are PC’s

ANSWER

Explanation

(1)Configure two routers on the left and right with these commands:

Router1 = router on the left

(2)Assign appropriate IP addresses to Fa0/0 & Fa0/1 interfaces:

Router enable
Router1#configure terminal
Router1(config)#interface fa0/0
Router1(config-if)#ip address 192 168.152.190 255.255.255.240
Router1(config-if)#no shutdown

Router1(config-if)#interface fa0/1
Router1(config-if)#ip address 192.168.152.142 255.255.255.240
Router1(config-if)#no shutdown

(3)Set passwords (configure on two routers)

+ Console password:

Router1(config-if)#exit
Router1(config)#line console 0
Router1(config-line)#password consolepw
Router1(config-line)#login
Router1(config-line #exit

+ Telnet password:

Router1(config)#line vty 04
Router1(config-line)#password telnetpw
Router1(config-line #login
Router1(config-line #exit

+ Privilege mode password:

Router1(config)#nable password privpw

Save the configuration:

Router1(config)#exit
Routeri#copy running-config startup-config

(4) Configure IP addresses of Router2 (router on the right)

Router2>enable
Router2#configure terminal
Router2(config)#interface fa0/0
Router2(config-if)#ip address 192.168.152 238 255.255.255.240
Router2(config-if)#no shutdown

Router2(config-if)#interface serial0/0
Router2(config-if)#ip address 192.168. 152. 174 255 255 255 240
Router2(config-if)#no shutdown

162. To what type of port would a cable with a DB-60 connector attach?

  • Serial port
  • Console port
  • Ethernet port
  • Fibre optic port

163. A network administrator is connecting PC hosts A and B directly through their Ethernet interfaces as shown in the graphic. Ping attempts between the hosts are unsuccessful. What can be done to provide connectivity between the hosts? (Choose two.)

  • A crossover cable should be used in place of the straight-through cable.
  • A rollover cable should be used in place of the straight-through cable.
  • The subnet masks should be set to 255.255.255.192
  • A default gateway needs to be set on each host.
  • The hosts must be reconfigured to use private IP addresses for direct connections of this type.
  • The subnet masks should be set to 255.255.255.0

164. Refer to the exhibit. What kind of cable should be used to make each connection that is identified by the numbers shown?

  • 1 – Ethernet Crossover cable
    2- Ethernet straight-through cable
    3- Fiber Optic cable
    4- Rollover cable
  • 1 – Ethernet straight-through cable
    2- Ethernet straight-through cable
    3- Serial cable
    4- Rollover cable
  • 1 – Ethernet rollover cable
    2- Ethernet crossover cable
    3- Serial cable
    4- Null-modem cable
  • 1 – Ethernet straight-through cable
    2- Ethernet Crossover cable
    3- Serial cable
    4- Rollover cable
  • 1 – Ethernet straight-through cable
    2- Ethernet Crossover cable
    3- Serial cable
    4- Ethernet Straight-through cable

165. Which of the following are types of flow control? (Choose three.)

  • buffering
  • cut-through
  • windowing
  • congestion avoidance
  • load balancing

Explanation: http://www.info-it.net/cisco/ccnalexam-tips/flow-control.php

During Transfer of data, a high speed computer is generating data traffic a lot faster than the network device can handle in transferring to destination, so single gateway or destination device cannot handle much amount of traffic that is called “Congestion”.

Buffering
The Technie is used to control the data transfer when we have congestion, when a network device receive a data it stores in memory section and then transfer to next destination this process called “Buffering”
Windowing Whereas Windowing is used for flow control by the Transport layer. Say the sender device is sending segments and the receiver device can accommodate only a fixed number of segments before it can accept more, the two devices negotiate the window size during the connection setup.

This is done so that the sending device doesn’t overflow the receiving device’s buffer. Also the receiving device can send a single acknowledgement for the segments it has received instead of sending an acknowledgement after every segment received. Also, this window size is dynamic meaning, the devices can negotiate and change the window size in the middle of a session. So if initially the window size is three and the receiving device thinks that it can accept more number of segments in its buffer it can negotiate with the sending device and it increase it to say 5 for example. Windowing is used only by TCP since UDP doesn’t use or allow flow control.

166. How many simultaneous Telnet sessions does a Cisco router support by default?

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6

167. What is the purpose of flow control?

  • To ensure data is retransmitted if an acknowledgement is not received.
  • To reassemble segments in the correct order at the destination device.
  • To provide a means for the receiver to govern the amount of data sent by the sender.
  • To regulate the size of each segment.

Explanation: http://whatis.techtarget.com/definition/flow-control Flow control is the management of data flow between computers or devices or between nodes in a network so that the data can be handled at an efficient pace. Too much data arriving before a device can handle it causes data overflow, meaning the data is either lost or must be retransmitted. For serial data transmission locally or in a network, the Xon/Xoff protocol can be used. For modem connections, either Xon/off or CTS/RTS (Clear to Send/Ready to Send) commands can be used to control data flow. In a network, flow control can also be applied by refusing additional device connections until the flow of traffic has subsided.

168. Refer to the exhibit. How many collision domains are shown?

  • one
  • two
  • three
  • four
  • six
  • twelve

Explanation: Hubs create single collision and broadcast domains.

169. Which IP address is a private address?

  • 12.0.0.1
  • 168.172.19.39
  • 172.20.14.36
  • 172.33.194.30
  • 192.169.42.34

Explanation: Private IP Address Ranges (REC 1918)

170. Which statement is true?

  • An IPv6 address is 64 bits long and is represented as hexadecimal characters.
  • An IPv6 address is 32 bits long and is represented as decimal digits.
  • An IPv6 address is 128 bits long and is represented as decimal digits.
  • An IPv6 address is 128 bits long and is represented as hexadecimal characters.

Explanation: http://www.cisco.com/en/US/technologies/tk648/tk872/technologies_white_paper0900aecd 8026003d.pdf

One of the key advantages IPv6 brings is the exponentially larger address space. The following will outline the basic address architecture of IPv6.
128-bit-long addresses
Represented in hexadecimal format: Uses CIDR principles prefix/prefix length x:x:x:x:x:x:x:x, where x is a 16-bit hex field The last 64 bits are used for the interface ID

171. If an Ethernet port on a router was assigned an IP address of 172.16.112.1/20, what is the maximum number of hosts allowed on this subnet?

  • 1024
  • 2046
  • 4094
  • 4096
  • 8190

Explanation: Each octet represents eight bits. The bits, in turn, represent (from left to right): 128, 64, 32, 16, 8, 4,2,1

Add them up and you get 255. Add one for the all zeros option, and the total is 256. Now take away one of these for the network address (all zeros) and another for the broadcast address (all ones). Each octet represents 254 possible hosts. Or 254 possible networks. Unless you have subnet zero set on your network gear, in which case you could conceivably have 255. The CIDR addressing format (20) tells us that 20 bits are used for the network portion, so the maximum number of networks are 2420 minus one if you have subnet zero enabled, or minus 2 if not. You asked about the number of hosts. That will be 32 minus the number of network bits, minus two. So calculate it as (24(32-20))-2, or (2012)-2 = 4094

172. Which statements are TRUE regarding Internet Protocol version 6 (IPv6) addresses? (Choose three.)

  • An IPv6 address is divided into eight 16-bit groups.
  • A double colon (::) can only be used once in a single IPv6 address.
  • IPv6 addresses are 196 bits in length.
  • Leading zeros cannot be omitted in an IPv6 address.
  • Groups with a value of 0 can be represented with a single 0 in IPv6 address.

Explanation: IPv6 addresses are divided into eight 16-bit groups, a double colon (::) can only be used once in an IPv6 address, and groups with a value of 0 can be represented with a single 0 in an IPv6 address. The following statements are also true regarding IPv6 address:

IPv6 addresses are 128 bits in length.
Eight 16-bit groups are divided by a colon (:).
Multiple groups of 16-bit Os can be represented with double colon (::).
Double colons (::) represent only Os.
Leading zeros can be omitted in an IPv6 address.
The option stating that IPv6 addresses are 196 bits in length is incorrect. IPv6 addresses are 128 bits in length.
The option stating that leading zeros cannot be omitted in an IPv6 address is incorrect. Leading zeros can be omitted in an IPv6 address.

173. Which of the following IP addresses are valid Class B host addresses if a default Class B mask is in use? (Choose two.)

  • 10.6.8.35
  • 133.6.5.4
  • 192.168.5.9
  • 127.0.0.1
  • 190.6.5.4

Explanation: The IP addresses 133.6.5.4 and 190.6.5.4 are both valid Class B addresses when a default mask is in use.

The Class B default mask is 255.255.0.0 and the range of valid addresses is 128.0.0.0- 191.255.255.255.

The IP address 10.6.8.35 is a Class A address. The Class A default mask is 255.0.0.0 and the range of valid addresses is 1.0.0.0 – 127.255.255.255, with the exception of the range 127.0.0.1 – 127.255.255.255, which is reserved and cannot be assigned. The IP address 192.168.5.9 is a Class C address. The Class C default mask is 255.255.255.0 and the range of valid addresses is 192.0.0.0 – 223.255.255.255. The IP address 127.0.0.1 is a Class A address, but it comes from a reserved portion that cannot be assigned.

The range 127.0.0.1 – 127.255.255.255 is used for diagnostics, and although any address in the range will work as a diagnostic address, 127.0.0.1 is known as the loopback address. If you can ping this address, or any address in the 127.0.0.1 – 127.255.255.255 range, then the NIC is working and TCP/IP is installed. The Class A default mask is 255.0.0.0 and the range of valid addresses is 1.0.0.0 127.255.255.255, with the exception of the range 127.0.0.1 – 127.255.255.255, which is reserved and cannot be assigned.

174. How many addresses will be available for dynamic NAT translation when a router is configured with the following commands?

Router (config)#ip nat pool TAME 209.165.201.23 209.165.201.30 netmask 255.255.255.224 
Router (config)#ip nat inside source list 9 pool TAME
  • 7
  • 8
  • 9
  • 10
  • 24
  • 32

Explanation: 209.165.201.23 to 209.165.201.30 provides for 8 addresses.

175. Some routers have been configured with default routes. What are some of the advantages of using default routes? (Choose two)

  • They establish routes that will never go down.
  • They keep routing tables small.
  • They require a great deal of CPU power.
  • They allow connectivity to remote networks that are not in the routing table
  • They direct traffic from the internet into corporate networks.

Explanation: Cisco administration 101: What you need to know about default routes
http://www.techrepublic.com/article/cisco-administration-101-what-you-need-to-know-aboutdefault-routes/

176. Refer to the exhibit. PC1 pings PC2. What three things will CORE router do with the data that is received from PC1? (Choose three.)

  • The data frames will be forwarded out interface FastEthernet0/1 of CORE router.
  • The data frames will be forwarded out interface FastEthernet1/0 of CORE router.
  • CORE router will replace the destination IP address of the packets with the IP address of PC2.
  • CORE router will replace the MAC address of PC2 in the destination MAC address of the frames.
  • CORE router will put the IP address of the forwarding FastEthernet interface in the place of the source IP address in the packets.
  • CORE router will put the MAC address of the forwarding FastEthernet interface in the place of the source MAC address.

177. Which three statements are correct about RIP version 2? (Choose three)

  • It uses broadcast for its routing updates.
  • It supports authentication.
  • It is a classless routing protocol.
  • It has a lower default administrative distance then RIP version 1.
  • It has the same maximum hop count as RIP version 1.
  • It does not send the subnet mask any updates.

178. Refer to the exhibit. Why are two OSPF designated routers identified on Core-Router?

  • Core-Router is connected to more than one multi-access network.
  • The router at 208.149.23.130 is a secondary DR in case the primary fails.
  • Two router IDs have the same OSPF priority and are therefore tied for DR election
  • The DR election is still underway and there are two contenders for the role.

Explanation: OSPF elects one DR per multi-access network. In the exhibit there are two DR so there must have more than one multi-access network.

179. What is the OSPF default frequency, in seconds, at which a Cisco router sends hello packets on a multi-access network?

  • 10
  • 40
  • 30
  • 20

Explanation: On broadcast multiacess and point-to-point links, the default is 10 seconds. On NBMA, the default is 30 seconds.

180. What does the “Inside Global” address represent in the configuration of NAT?

  • the summarized address for all of the internal subnetted addresses
  • the MAC address of the router used by inside hosts to connect to the Internet
  • a globally unique, private IP address assigned to a host on the inside network
  • a registered address that represents an inside host to an outside network

Explanation: NAT: Local and Global Definitions http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094837.shtml

Cisco defines these terms as:

Inside local address–The IP address assigned to a host on the inside network. This is the address configured as a parameter of the computer OS or received via dynamic address allocation protocols such as DHCP. The address is likely not a legitimate IP address assigned by the Network Information Center (NIC) or service provider. Inside global address–A legitimate IP address assigned by the NIC or service provider that represents one or more inside local IP addresses to the outside world. Outside local address–The IP address of an outside host as it appears to the inside network. Not necessarily a legitimate address, it is allocated from an address space routable on the inside.

Outside global address–The IP address assigned to a host on the outside network by the host owner.

The address is allocated from a globally routable address or network space. These definitions still leave a lot to be interpreted. For this example, this document redefines these terms by first defining local address and global address. Keep in mind that the terms inside and outside are NAT definitions. Interfaces on a NAT router are defined as inside or outside with the NAT configuration commands, ip nat inside destination and ip nat outside source Networks to which these interfaces connect can then be thought of as inside networks or outside networks, respectively. Local address–A local address is any address that appears on the inside portion of the network. Global address–A global address is any address that appears on the outside portion of the network.

181. Refer to the exhibit. A company wants to use NAT in the network shown. Which commands will apply the NAT configuration to the proper interfaces? (Choose two.)

  • R1(config)# interface serial0/1 R1(config-if)# ip nat inside
  • R1(config)# interface serial0/1 R1(config-if)# ip nat outside
  • R1(config)# interface fastethernet0/0 R1(config-if)# ip nat inside
  • R1(config)# interface fastethernet0/0 R1(config-if)# ip nat outside
  • R1(config)# interface serial0/1
    R1(config-if)# ip nat outside source pool 200 2.2.18 255.255.255.252
  • R1(config)# interface fastethernet0/0
    R1(config-if)# ip nat inside source 10.10.0.0 255.255.255.0

182. Which of the following statements are TRUE regarding Cisco access lists? (Choose two.)

  • In an inbound access list, packets are filtered as they enter an interface.
  • In an inbound access list, packets are filtered before they exit an interface.
  • Extended access lists are used to filter protocol-specific packets.
  • You must specify a deny statement at the end of each access list to filter unwanted traffic.
  • When a line is added to an existing access list, it is inserted at the beginning of the access  list.

Explanation: In an inbound access list, packets are filtered as they enter an interface. Extended access lists are used to filter protocol specific packets. Access lists can be used in a variety of situations when the router needs to be given guidelines for decision-making. These situations include:

Filtering traffic as it passes through the router
To control access to the VTY lines (Telnet)
To identify “interesting” traffic to invoke Demand Dial Routing (DDR) calls
To filter and control routing updates from one router to another There are two types of access lists, standard and extended. Standard access lists are applied as close to the destination as possible (outbound), and can only base their filtering criteria on the source IP address. The number used while creating an access list specifies the type of access list created. The range used for standard access lists is 1 to 99 and 1300 to 1999. Extended access lists are applied as close to the source as possible (inbound), and can base their filtering criteria on the source or destination IP address, or on the specific protocol being used. The range used for extended access lists is 100 to 199 and 2000 to 2699.

Other features of access lists include:

Inbound access lists are processed before the packet is routed. Outbound access lists are processed after the packet has been routed to an exit interface. An “implicit deny” is at the bottom of every access list, which means that if a packet has not matched any preceding access list condition, it will be filtered (dropped). Access lists require at least one permit statement, or all packets will be filtered (dropped). One access list may be configured per direction for each Layer 3 protocol configured on an interface The option stating that in an inbound access list, packets are filtered before they exit an interface is incorrect.

Packets are filtered as they exit an interface when using an outbound access list. The option stating that a deny statement must be specified at the end of each access list in order to filter unwanted traffic is incorrect. There is an implicit deny at the bottom of every access list. When a line is added to an existing access list, it is not inserted at the beginning of the access list. It is inserted at the end. This should be taken into consideration. For example, given the following access list, executing the command access-list 110 deny tcp 192.168.5.0 0.0.0.255 any eq www would have NO effect on the packets being filtered because it would be inserted at the end of the list, AFTER the line that allows all traffic.

access-list 110 permit ip host 192.168.5.1 any access-list 110 deny icmp 192.168.5.0 0.0.0.255 any echo access-list 110 permit any any

183. From which of the following attacks can Message Authentication Code (MAC) shield your network?

  • Dos
  • DDoS
  • spoofing
  • SYN floods

Explanation: Message Authentication Code (MAC) can shield your network from spoofing attacks. Spoofing, also known as masquerading, is a popular trick in which an attacker intercepts a network packet, replaces the source address of the packets header with the address of the authorized host, and reinserts fake information which is sent to the receiver. This type of attack involves modifying packet contents. MAC can prevent this type of attack and ensure data integrity by ensuring that no data has changed. MAC also protects against frequency analysis, sequence manipulation, and ciphertext-only attacks. MAC is a secure message digest that requires a secret key shared by the sender and receiver, making it impossible for sniffers to change both the data and the MAC as the receiver can detect the changes.

A denial-of-service (DoS) attack floods the target system with unwanted requests, causing the loss of service to users. One form of this attack generates a flood of packets requesting a TCP connection with the target, tying up all resources and making the target unable to service other requests. MAC does not prevent DoS attacks. Stateful packet filtering is the most common defense against a DoS attack.

A Distributed Denial of Service attack (DDoS) occurs when multiple systems are used to flood the network and tax the resources of the target system. Various intrusion detection systems, utilizing stateful packet filtering, can protect against DDoS attacks. In a SYN flood attack, the attacker floods the target with spoofed IP packets and causes it to either freeze or crash. A SYN flood attack is a type of denial of service attack that exploits the buffers of a device that accept incoming connections and therefore cannot be prevented by MAC. Common defenses against a SYN flood attack include filtering, reducing the SYN-RECEIVED timer, and implementing SYN cache or SYN cookies.

184. Refer to the exhibit. After the power-on-self test (POST), the system LED of a Cisco 2950 switch turns amber. What is the status of the switch?

  • The POST was successful.
  • The switch has a problem with the internal power supply and needs an external power  supply to be attached.
  • POST failed and there is a problem that prevents the operating system from being loaded.
  • The switch has experienced an internal problem but data can still be forwarded at a slower rate.
  • The switch passed POST, but all the switch ports are busy.

Explanation:

http://www.cisco.com/en/US/products/hw/switches/ps607/products_tech_note09186a00801 25913.shtml

Each time you power up the switch, eight Power-On Self Tests (POSTs) run automatically POSTS check the most important system components before the switch begins to forward packets. When the switch begins the POST, the port status LEDs display amber for two seconds, and then display green. As each test runs, the port status LEDs go out 1x is the first to go out. The port status LEDs for ports 2x through 8x go out sequentially as the system completes a test. When the POST completes successfully, the port status LEDs go out. This indicates that the switch is operational. If a test fails, the port status LED associated with the test displays amber.

The system LED also displays amber. NotE. From Cisco IOS Software Release 11.218.5) SA6 onwards, the port and system LEDs both remain amber after a POST failure. In the earlier Cisco IOS Software Releases, only the LEDs of failed linked ports remained amber.

185. Refer to the exhibit. A technician pastes the configurations in the exhibit into the two new routers shown. Otherwise, the routers are configured with their default configurations.

A ping from Host1 to Host 2 fails, but the technician is able to ping the S0/0 interface of R2 from Host 1. The configurations of the hosts have been verified as correct. What could be the cause of the problem?

  • The serial cable on R1 needs to be replaced.
  • The interfaces on R2 are not configured properly
  • R1 has no route to the 192.168.1.128 network.
  • The IP addressing scheme has overlapping subnetworks.
  • The ip subnet-zero command must be configured on both routers.

Explanation: Without a static route pointing to host 2 network the router is unaware of the path to take to reach that network and reply traffic cannot be sent.

186. Refer to the exhibit. Why did the device return this message?

  • The command requires additional options or parameters
  • There is no show command that starts with ru.
  • The command is being executed from the wrong router mode.
  • There is more than one show command that starts with the letters ru.

Explanation: Answer D is correct because when you type the incomplete command having more same more command same up to types characters it shows display the ambiguous command error.

187. Refer to the exhibit. Serial 0/0 does not respond to a ping request from a host on the FastEthernet 0/0 LAN. How can this problem be corrected?

  • Enable the Serial 0/0 interface.
  • Correct the IP address for Serial 0/0.
  • Correct the IP address for FastEthernet 0/0
  • Change the encapsulation type on Serial 0/0
  • Enable autoconfiguration on the Serial 0/0 interface

Explanation: Serial 0/0 interface is administratively down therefore, you will have to run the “no shutdown” command to enable the interface for data.

188. Refer to the exhibit. Why was this message received?

  • No VTY password has been set.
  • No enable password has been set.
  • No console password has been set.
  • No enable secret password has been set.
  • The login command has not been set on CON 0
  • The login command has not been set on the VTY ports.

189. Refer to the exhibit. After configuring two interfaces on the HQ router, the network administrator notices an error message. What must be done to fix this error?

  • The serial interface must be configured first.
  • The serial interface must use the address 192.168.1.2
  • The subnet mask of the serial interface should be changed to 255.255.255.0
  • The subnet mask of the FastEthernet interface should be changed to 255.255.255.240
  • The address of the FastEthernet interface should be changed to 192.168.1.66

190. Two routers named Atlanta and Brevard are connected by their serial interfaces as shown in the exhibit, but there is no data connectivity between them. The Atlanta router is known to have a correct configuration.

Given the partial configurations shown in the exhibit, what is the problem on the Brevard router that is causing the lack of connectivity?

  • A loopback is not set.
  • The IP address is incorrect.
  • The subnet mask is incorrect.
  • The serial line encapsulations are incompatible.
  • The maximum transmission unit (MTU) size is too large.
  • The bandwidth setting is incompatible with the connected interface.

191. What are two benefits of using a single OSPF area network design? (Choose two.)

  • It is less CPU intensive for routers in the single area.
  • It reduces the types of LSAs that are generated.
  • It removes the need for virtual links.
  • It increases LSA response times.
  • It reduces the number of required OSPF neighbor adjacencies.

192. What command sequence will configure a router to run OSPF and add network 10.1.1.0/24 to area 0?

  • router ospf area 0 network 10.1.1.0 255.255.255.0 area 0
  • router ospf network 10.1.1.0 0.0.0.255
  • router ospf 1 network 10.1.1.0 0.0.0.255 area 0
  • router ospf area 0 network 10.1.1.0 0.0.0.255 area 0
  • router ospf network 10.1.1.0 255.255.255.0 area 0
  • router ospf 1 network 10.1.1.0 0.0.0.255

193. Refer to the exhibit. If the router Cisco returns the given output and has not had its router ID set manually, what value will OSPF use as its router ID?

  • 192.168.1.1
  • 172.16.1.1
  • 1.1.1.1
  • 2.2.2.2

194. What OSPF command, when configured, will include all interfaces into area 0?

  • network 0.0.0.0 255.255.255.255 area 0
  • network 0.0.0.0 0.0.0.0 area 0
  • network 255.255.255.255 0.0.0.0 area o
  • network all-interfaces area 0

195. Which statement describes the process ID that is used to run OSPF on a router?

  • It is globally significant and is used to represent the AS number.
  • It is locally significant and is used to identify an instance of the OSPF database.
  • It is globally significant and is used to identify OSPF stub areas.
  • It is locally significant and must be the same throughout an area.

196. Hotspot

Refer to the topology. Your company has decided to connect the main office with three other remote branch offices using point-to-point serial links.

You are required to troubleshoot and resolve OSPF neighbor adjacency issues between the main office and the routers located in the remote branch offices.

An OSPF neighbor adjacency is not formed between R3 in the main office and R5 in the Branch2 office. What is causing the problem?

  • There is an area ID mismatch.
  • There is a PPP authentication issue, a password mismatch.
  • There is an OSPF hello and dead interval mismatch.
  • There is a missing network command in the OSPF process on R5.

Explanation: The “show ip ospf interface command on R3 and R5 shows that the hello and dead intervals do not match. They are 50 and 200 on R3 and 10 and 40 on R5.

197. Hotspot

Refer to the topology. Your company has decided to connect the main office with three other remote branch offices using point-to-point serial links.

You are required to troubleshoot and resolve OSPF neighbor adjacency issues between the main office and the routers located in the remote branch offices.

R1 does not form an OSPF neighbor adjacency with R2. Which option would fix the issue?

  • R1 ethernet0/1 is shutdown. Configure no shutdown command.
  • R1 etherneto/1 configured with a non-default OSPF hello interval of 25: configure no ip ospf hello-interval 25
  • R2 ethernet0/1 and R3 ethernetO/O are configured with a non-default OSPF hello interval of 25; configure no ip ospf hello-interval 25
  • Enable OSPF for R1 ethernet0/1; configure ip ospf 1 area 0 command under ethernet0/1

Explanation: Looking at the configuration of R1, we see that R1 is configured with a hello interval of 25 on interface Ethernet 0/1 while R2 is left with the default of 10 (not configured).

198. Hotspot

Refer to the topology. Your company has decided to connect the main office with three other remote branch offices using point-to-point serial links.

You are required to troubleshoot and resolve OSPF neighbor adjacency issues between the main office and the routers located in the remote branch offices.

An OSPF neighbor adjacency is not formed between R3 in the main office and R6 in the Branch3 office. What is causing the problem?

  • There is an area ID mismatch.
  • There is a PPP authentication issue; the username is not configured on R3 and R6.
  • There is an OSPF hello and dead interval mismatch.
  • The R3 router ID is configured on R6.

Explanation: Using the show running-config command we see that R6 has been incorrectly configured with the same router ID as R3 under the router OSPF process.

199. After the show ip route command has been entered the following routes are displayed. Which route will not be entered into the routing table of a neighboring router?

  • R 192.168.8.0/24 [120/1] via 192.168.2.2, 00:00:10, Serialo
  • R 192.168.11.0/24 [120/7] via 192.168.9.1, 00:00:03, Serial1
  • C 192.168.1.0/24 is directly connected, Ethernet0
  • R 192.168.5.0/24 [120/15] via 192.168.2.2, 00:00:10, Serialo

Explanation: The route 192.168.5.0/24 currently has the metric of 15 so this router will add 1 hop count before sending out to its neighboring router. With RIP, a metric of 16 means that network is down -> it will not be installed in the routing table of the neighboring router.

200. Refer to Exhibit. Based on the network shown in the graphic which option contains both the potential networking problem and the protocol or setting that should be used to prevent the problem?

  • routing loops, hold down timers
  • switching loops, split horizon
  • routing loops, split horizon
  • switching loops, VTP
  • routing loops, STP
  • switching loops, STP

201. If all OSPF routers in a single area are configured with the same priority value, what value does a router use for the OSPF router ID in the absence of a loopback interface?

  • the IP address of the first Fast Ethernet interface
  • the IP address of the console management interface
  • the highest IP address among its active interfaces
  • the lowest IP address among its active interfaces
  • the priority value until a loopback interface is configured

202. The OSPF Hello protocol performs which of the following tasks? (Choose two.)

  • It provides dynamic neighbor discovery.
  • It detects unreachable neighbors in 90 second intervals.
  • It maintains neighbor relationships.
  • It negotiates correctness parameters between neighboring interfaces.
  • It uses timers to elect the router with the fastest links as the designated router.
  • It broadcasts hello packets throughout the internetwork to discover all routers that are running OSPF.

203. Which of the following is a characteristic of full-duplex communication?

  • It is a CSMA/CD network.
  • It is a CSMA/CA network.
  • It is point-to-point only.
  • Hub communication is done via full duplex.

204. Which commands display information about the Cisco IOS software version currently running on a router? (Choose three.)

  • show running-config
  • show stacks
  • show version
  • show flash
  • show protocols
  • show IOS

205. After the shutdown command has been issued on the serial 0/0 interface, what will be displayed when the show interface serial 0/0 command is issued by the administrator?

  • Serial0/0 is administratively down, line protocol is down
  • Serial0/0 is down, line protocol is down
  • Serial0/0 is up, line protocol is down
  • Serial0/0 is administratively down, line protocol is administratively down
  • Serial0/0 is up, line protocol is up
  • Serial0/0 is down, line protocol is up

206. Refer to the output of the three router commands shown in the exhibit. A new technician has been told to add a new LAN to the company router. Why has the technician received the error message that is shown following the last command?

  • The interface was already configured.
  • The interface type does not exist on this router platform.
  • The IOS software loaded on the router is outdated.
  • The router does not support LAN interfaces that use Ethernet.
  • The command was entered from the wrong prompt.

Explanation: From the output of the “show version” command, we learn that there are only 2 FastEthernet interfaces (2 FastEthernet/IEEE 802.3 interfaces) and this router does not have any Ethernet interface so an error will occur when we enter the “interface e0” command.

207. The system LED is amber on a Cisco Catalyst 2950 series switch. What does this indicate?

  • The system is malfunctioning.
  • The system is not powered up.
  • The system is powered up and operational.
  • The system is forwarding traffic.
  • The system is sensing excessive collisions.

Explanation:

The system LED shows whether the system is receiving power and functioning properly.
Below lists the LED colors and meanings:
Color
System Status Off
System is not powered up.
Green
System is operating normally. Amber
System is receiving power but is not functioning properly. http://www.cisco.com/en/US/docs/switches/lan/catalyst2950/hardware/installation/guide/hgovrev.html

208. Refer to the topology and partial configurations shown in the exhibit. The network administrator has finished configuring the NewYork and Sydney routers and issues the command ping Sydney from the NewYork router. The ping fails. What command or set of commands should the network administrator issue to correct this problem?

  • Sydney(config)# interface s0/0 Sydney(config-if)# cdp enable
  • Sydney(config)# interface s0/0 Sydney(config-if)# no shut
  • Sydney(config)# line vty 0 4 Sydney(config)# login
    Sydney(config)# password Sydney
  • Sydney(config)# ip host Sydney 10.1.1.9
  • Sydney(config)# interface s0/0
    Sydney(config-if)# ip address 10.1.1.5 255.255.255.252
    NewYork(config)# ip host Sydney 10.1.1.5

Explanation: The IP addresses on the two Serial interfaces of two routers are not in the same subnet so they could not recognize each other and the ping failed. Therefore we must correct the IP address of one of the router so that they are in the same subnet.

209. Refer to the topology and MAC address table shown in the exhibit. Host A sends a data frame to host D. What will the switch do when it receives the frame from host A?

  • The switch will add the source address and port to the MAC address table and forward the frame to host D.
  • The switch will discard the frame and send an error message back to host A.
  • The switch will flood the frame out of all ports except for port Fa0/3.
  • The switch will add the destination address of the frame to the MAC address table and forward the frame to host D.

210. Refer to the exhibit. Host B has just been added to the network and must acquire an IP address. Which two addresses are possible addresses that will allow host B to communicate with other  devices in the network? (Choose two.)

  • 192.168.10.32
  • 192.168.10.38
  • 192.168.10.46
  • 192.168.10.47
  • 192.168.10.49
  • 192.168.10.51

Explanation: The IP address of host B must be in the range of 192.168.10.32/28 subnet, which ranges from 192.168.10.32 to 192.168.10.47 (Increment: 16), except the IP addresses of 192.168.10.32, 192.168.10.46 (which are the network and broadcast addresses of the subnet), 192.168.10.33, 192.168.10.34 (which have been assigned to the interface’s router and the switch). Therefore there are only two IP addresses of 192.168.10.38 & 192.168.10.46.

211. Refer to the exhibit. HostB is sending a file to HostA. B represents the frame as it leaves the Oshawa router. What is the Layer 2 destination address of the frame at this point?

  • abcd.1123.0045
  • abcd.1234.5678
  • abcd.2246.0035
  • abcd.4444.0012
  • aabb.5555.2222

212. Refer to the exhibit. A network technician is unable to ping from R1 to R2. Using the output of the show interfaces serial0/1 command, what should the administrator do to correct the problem?

  • Replace the serial cable between R1 and R2.
  • Reseat the serial connectors on the R1 and R2 routers.
  • Configure the serial0/1 interface on R2 with the no shutdown command.
  • Configure the serial0/1 interface on R1 with the clock rate 56000 command.
  • Configure the serial0/1 interface on R1 with the ip address 192.1.1.7 255.255.255.252 command.

213. Examine the network diagram and router output shown in the exhibit. Users on the BHM LAN are unable to access the server attached to the BHE router. What two things should be done to fix this problem? (Choose two.)

  • Enter the configuration mode for interface fastethernet0/0
  • Enter the configuration mode for interface serial0/0
  • Enter the configuration mode for interface serial0/1.
  • Issue the run command.
  • Issue the enable command.
  • Issue the no shutdown command.

214. From where does a small network get its IP network address?

  • Internet Assigned Numbers Authority (IANA)
  • Internet Architecture Board (IAB)
  • Internet Service Provider (ISP)
  • Internet Domain Name Registry (IDNR)

215. A network administrator has subnetted the 172.16.0.0 network using a subnet mask of 255.255.255.192. A duplicate IP address of 172.16.2.120 has accidentally been configured on a workstation in the network. The technician must assign this workstation a new IP address within that same subnetwork. Which address should be assigned to the workstation?

  • 172.16.1.80
  • 172.16.1.64
  • 172.16.2.64
  • 172.16.2.127
  • 172.16.2.128
  • 172.16.2.80

216. Refer to the exhibit. A network technician is unable to ping from R1 to R2. What will help correct the problem?

  • Ensure that the serial cable is correctly plugged in to the interfaces.
  • Apply the clock rate 56000 configuration command to the serial0/1 interface of R1.
  • Configure the serial0/1 interfaces on R1 and R2 with the no shutdown command.
  • Change the address of the serial0/1 interface of R1 to 192.1.1.4.
  • Change the subnet masks of both interfaces to 255.255.255.240.

217. SW-C has just been added to the network shown in the graphic.

What is the purpose of assigning a default gateway to this switch?

  • allows connectivity to Router B from the switch prompt
  • allows console port connectivity to the switch from Host A
  • allows connectivity to remote network devices from Host B
  • allows the switch to pass traffic between Host A and Host B

218. What is the maximum number of bits that can be borrowed to create subnets if a Class B network address is being used?

  • 2
  • 6
  • 8
  • 14
  • 16

219. Which three network addresses are reserved for private network use? (Choose three.)

  • 10.0.0.0
  • 172.15.0.0
  • 172.31.0.0
  • 192.162.24.0
  • 192.168.255.0
  • 224.192.0.0

220. Which form of NAT maps multiple private IP addresses to a single registered IP address by using different ports?

  • static NAT
  • dynamic NAT
  • overloading
  • overlapping
  • port loading

221. Refer to the exhibit. A network technician has added host A to the network. Host A cannot communicate on the network. A ping that is issued on the host to address 127.0.0.1 fails. What is the problem?

  • The router is not forwarding the ping packets to network 127.0.0.0.
  • The remote host at 127.0.0.1 is unreachable.
  • The default gateway is incorrect.
  • The IP address of host A is incorrect.
  • The TCP/IP protocols are not loaded.

222. Refer to the exhibit. Pierre has just installed the mail server and Switch2. For security reasons UDP packets are not permitted outbound on the Fa0/1 router interface. Pierre is now at his workstation testing the new installation and is not able to establish SMTP communication to the mail server.

What is the most likely cause for lack of communication between Pierre’s workstation and the mail server?

  • The crossover cable should be a straight-through cable.
  • UDP is blocked coming out of the Fa0/1 interface on the router.
  • The server should be directly connected to the router.
  • The IP addresses are all on the same network. No router is required.

223. Refer to the exhibits labeled A through E. All devices are to be connected over Ethernet. Which three device-to-device configurations are likely to require the use of a crossover connection? (Choose three.)

  • exhibit A
  • exhibit B
  • exhibit C
  • exhibit D
  • exhibit E

224. Refer to the exhibit. Which two statements are true of the interface configuration? (Choose two.)

  • The encapsulation in use on this interface is PPP.
  • The default serial line encapsulation is in use on this interface.
  • The address mask of this interface is 255.255.255.0.
  • This interface is connected to a LAN.
  • The interface is not ready to forward packets.

225. Refer to the exhibit. What value should be displayed in Box 1 of the ipconfig output of host A?

  • 172.18.14.5
  • 172.18.14.6
  • 192.168.1.10
  • 192.168.1.11
  • 192.168.1.250
  • 192.168.1.254

226. The internetwork shown in the diagram is experiencing network connectivity problems. What is the cause of the problem?

  • The cabling connecting host A to Switch3 is too long.
  • The address of host B is a broadcast address.
  • The IP address of interface Fa0/0 of Router1 is not a usable address.
  • The cable connecting Switch2 and Switch3 should be a crossover
  • The IP address of Server 1 is in the wrong subnet.

227. Refer to the exhibit. Which two of the output fields could help you determine if a broadcast storm has occurred? (Choose two.)

  • giants
  • no buffer
  • collisions
  • ignored
  • dribble condition

228. Refer to the exhibit. What does the address 192.168.2.167 represent?

  • the TFTP server from which the file startup-config is being transferred
  • the router from which the file startup-config is being transferred
  • the TFTP server from which the file router-confg is being transferred
  • the TFTP server to which the file router-confg is being transferred
  • the router to which the file router-confg is being transferred
  • the router to which the file startup-config is being transferred

229. Refer to the exhibit. Two 2950 switches connect through ports fa0/24 using a straight-through cable. Based on the output that is shown in the exhibit and the information that is given, what can be concluded about this network?

  • STP can not be configured on a FastEthernet ports.
  • An IP address and default gateway must be configured on each switch.
  • The switches do not share the same VTP domain.
  • Port fa0/24 must be configured as a trunk in order for the switches to share neighbor information.
  • The switches are cabled incorrectly.

230. In which situation would the use of a static route be appropriate?

  • To configure a route to the first Layer 3 device on the network segment.
  • To configure a route from an ISP router into a corporate network.
  • To configure a route when the administrative distance of the current routing protocol is too low.
  • To reach a network is more than 15 hops away.
  • To provide access to the Internet for enterprise hosts.

231. Which NTP command configures the local device as an NTP reference clock source?

  • ntp peer
  • ntp broadcast
  • ntp master
  • ntp server

232. Which routing protocol has the smallest default administrative distance?

  • IBGP
  • OSPF
  • IS-IS
  • EIGRP
  • RIP

Explanation:

http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/15986 admindistance.html

233. Which statement about static routes is true?

  • The source interface can be configured to make routing decisions.
  • A subnet mask is entered for the next-hop address.
  • The subnet mask is 255.255 255.0 by default
  • The exit interface can be specified to indicate where the packets will be routed.

Explanation: Static routing can be used to define an exit point from a router when no other routes are available or necessary. This is called a default route.

234. Under which circumstance should a network administrator implement one-way NAT?

  • when the network must route UDP traffic
  • when traffic that originates outside the network must be routed to internal hosts
  • when traffic that originates inside the network must be routed to internal hosts
  • when the network has few public IP addresses and many private IP addresses require outside access

Explanation: NAT operation is typically transparent to both the internal and external hosts. Typically the internal host is aware of the true IP address and TCP or UDP port of the external host. Typically the NAT device may function as the default gateway for the internal host. However the external host is only aware of the public IP address for the NAT device and the particular port being used to communicate on behalf of a specific internal host.

NAT and TCP/UDP
“Pure NAT”, operating on IP alone, may or may not correctly parse protocols that are totally concerned with IP information, such as ICMP, depending on whether the payload is interpreted by a host on the “inside” or “outside of translation. As soon as the protocol stack is traversed, even with such basic protocols as TCP and UDP, the protocols will break unless NAT takes action beyond the network layer. IP packets have a checksum in each packet header, which provides
error detection only for the header. IP datagrams may become fragmented and it is necessary for a NAT to reassemble these fragments to allow correct recalculation of higher-level checksums and correct tracking of which packets belong to which connection. The major transport layer protocols, TCP and UDP, have a checksum that covers all the data they carry, as well as the TCP/UDP header, plus a “pseudo-header” that contains the source and destination IP addresses of the packet carrying the TCP/UDP header. For an originating NAT to pass TCP or UDP successfully, it must recompute the TCP/UDP header checksum based on the translated IP addresses, not the original ones, and put that checksum into the TCP/UDP header of the first packet of the fragmented set of packets. The receiving NAT must recompute the IP checksum on every packet it passes to the destination host, and also recognize and recompute the TCP/UDP header using the retranslated addresses and pseudo-header. This is not a completely solved problem. One solution is for the receiving NAT to reassemble the entire segment and then recompute a checksum calculated across all packets.

The originating host may perform Maximum transmission unit (MTU) path discovery to determine the packet size that can be transmitted without fragmentation, and then set the don’t fragment (DF) bit in the appropriate packet header field. Of course, this is only a one-way solution, because the responding host can send packets of any size, which may be fragmented before reaching the NAT.

235. Which component of a routing table entry represents the subnet mask?

  • routing protocol code
  • prefix
  • metric
  • network mask

Explanation: IP Routing Table Entry TypesAn entry in the IP routing table contains the following information in the order presented:

Network ID. The network ID or destination corresponding to the route. The network ID can be class-based, subnet, or supernet network ID, or an IP address for a host route. Network Mask. The mask that is used to match a destination IP address to the network ID. Next Hop. The IP address of the next hop. Interface. An indication of which network interface is used to forward the IP packet. Metric. A number used to indicate the cost of the route so the best route among possible multiple routes to the same destination can be selected. A common use of the metric is to indicate the number of hops (routers crossed) to the network ID. Routing table entries can be used to store the following types of routes:

Directly Attached Network IDs. Routes for network IDs that are directly attached. For directly attached networks, the Next Hop field can be blank or contain the IP address of the interface on that network Remote Network IDs. Routes for network IDs that are not directly attached but are available across other routers. For remote networks, the Next Hop field is the IP address of a local router in between the forwarding node and the remote network. Host Routes. A route to a specific IP address. Host routes allow routing to occur on a per- IP address basis. For host routes, the network ID is the IP address of the specified host and the network mask is 255.255.255.255. Default Route. The default route is designed to be used when a more specific network ID or host route is not found. The default route network ID is 0.0.0.0 with the network mask of 0.0.0.0.

236. When a router makes a routing decision for a packet that is received from one network and destined to another, which portion of the packet does if replace?

  • Layer 2 frame header and trailer
  • Layer 3 IP address
  • Layer 5 session
  • Layer 4 protocol

Explanation: Router Switching Function (1.2.1.1) A primary function of a router is to forward packets toward their destination. This is accomplished by using a switching function, which is the process used by a router to accept a packet on one interface and forward it out of another interface. A key responsibility of the switching function is to encapsulate packets in the appropriate data link frame type for the outgoing data link.

NOTE:

In this context, the term “switching” literally means moving packets from source to destination and should not be confused with the function of a Layer 2 switch. After the router has determined the exit interface using the path determination function, the router must encapsulate the packet into the data link frame of the outgoing interface. What does a router do with a packet received from one network and destined for another network? The router performs the following three major steps:

Step 1. De-encapsulates the Layer 3 packet by removing the Layer 2 frame header and trailer.

Step 2. Examines the destination IP address of the IP packet to find the best path in the routing table.

Step 3. If the router finds a path to the destination, it encapsulates the Layer 3 packet into a new Layer 2 frame and forwards the frame out the exit interface.

237. On which type of device is every port in the same collision domain?

  • a router
  • a Layer 2 switch
  • a hub
  • switch
  • a Layer 3 switch

Explanation: Collision domainA collision domain is, as the name implies, a part of a network where packet collisions can occur. A collision occurs when two devices send a packet at the same time on the shared network segment. The packets collide and both devices must send the packets again, which reduces network efficiency. Collisions are often in a hub environment, because each port on a hub is in the same collision domain. By contrast, each port on a bridge, a switch or a router is in a separate collision domain.

238. Which statement about routing protocols is true?

  • Link-state routing protocols choose a path by the number of hops to the destination.
  • OSPF is a link-state routing protocol.
  • Distance-vector routing protocols use the shortest Path First algorithm
  • IS-IS is a distance-vector routing protocol.

Explanation:

Link State Routing Protocols
Link state protocols are also called shortest-path-first protocols. Link state routing protocols have a complete picture of the network topology. Hence they know more about the whole network than any distance vector protocol.

Three separate tables are created on each link state routing enabled router. One table is used to hold details about directly connected neighbors, one is used to hold the topology of the entire internetwork and the last one is used to hold the actual routing table. Link state protocols send information about directly connected links to all the routers in the network. Examples of Link state routing protocols include OSPF – Open Shortest Path First and IS-IS – Intermediate System to Intermediate System. There are also routing protocols that are considered to be hybrid in the sense that they use aspects of both distance vector and link state protocols. EIGRP – Enhanced Interior Gateway Routing Protocol is one of those hybrid routing protocols.

239. Which technology supports the stateless assignment of IPv6 addresses?

  • DNS
  • DHCPv6
  • DHCP
  • autoconfiguration

Explanation:

DHCPv6 Technology Overview
IPv6 Internet Address Assignment Overview
IPv6 has been developed with Internet Address assignment dynamics in mind. Being aware that IPv6 Internet addresses are 128 bits in length and written in hexadecimals makes automation of address-assignment an important aspect within network design. These attributes make it inconvenient for a user to manually assign IPv6 addresses, as the format is not naturally intuitive to the human eye. To facilitate address assignment with little or no human intervention, several methods and technologies have been developed to automate the process of address and configuration parameter assignment to IPv6 hosts. The various IPv6 address assignment methods are as follows:

1. Manual Assignment
An IPv6 address can be statically configured by a human operator. However, manual assignment is quite open to errors and operational overhead due to the 128 bit length and hexadecimal attributes of the addresses, although for router interfaces and static network elements and resources this can be an appropriate solution.

2. Stateless Address Autoconfiguration (RFC2462)
Stateless Address Autoconfiguration (SLAAC) is one of the most convenient methods to assign Internet addresses to IPv6 nodes. This method does not require any human intervention at all from an IPv6 user. If one wants to use IPv6 SLAAC on an IPv6 node, it is important that this IPv6 node is connected to a network with at least one IPv6 router connected. This router is configured by the network administrator and sends out Router Advertisement announcements onto the link. These announcements can allow the on-link connected IPv6 nodes to configure themselves with IPv6 address and routing parameters, as specified in RFC2462, without further human intervention.

3.Stateful DHCPv6
The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) has been standardized by the IETF through RFC3315. DHCPv6 enables DHCP servers to pass configuration parameters, such as IPv6 network addresses, to IPv6 nodes. It offers the capability of automatic allocation of reusable network addresses and additional configuration flexibility. This protocol is a stateful counterpart to “IPv6 Stateless Address Autoconfiguration” (RFC 2462), and can be used separately, or in addition to the stateless autoconfiguration to obtain configuration parameters.

4.DHCPv6-PD
DHCPv6 Prefix Delegation (DHCPv6-PD) is an extension to DHCPv6, and is specified in RFC3633. Classical DHCPv6 is typically focused upon parameter assignment from a DHCPv6 server to an IPv6 host running a DHCPv6 protocol stack. A practical example would be the stateful address assignment of 2001:db8:1″ from a DHCPv6 server to a DHCPv6 client. DHCPv6-PD however is aimed at assigning complete subnets and other network and interface parameters from a DHCPv6-PD server to a DHCPv6-PD client. This means that instead of a single address assignment, DHCPv6-PD will assign a set of IPv6 “subnets”. An example could be the assignment of “2001:db8::/60” from a DHCPv6-PD server to a DHCPv6-PD client. This will allow the DHCPv6 PD client (often a CPE device) to segment the received address IPv6 address space, and assign it dynamically to its IPv6 enabled interfaces.

5. Stateless DHCPv6
Stateless DHCPv6 is a combination of “stateless Address Autoconfiguration” and “Dynamic Host Configuration Protocol for IPv6” and is specified by RFC3736. When using stateless-DHCPv6, a device will use Stateless Address Auto-Configuration (SLAAC) to assign one or more IPv6 addresses to an interface, while it utilizes DHCPv6 to receive “additional parameters” which may not be available through SLAAC. For example, additional parameters could include information such as DNS or NTP server addresses, and are provided in a stateless manner by DHCPv6. Using stateless DHCPv6 means that the DHCPv6 server does not need to keep track of any state of assigned IPv6 addresses, and there is no need for state refreshment as result. On network media supporting a large number of hosts associated to a single DHCPv6 server, this could mean a significant reduction in DHCPv6 messages due to the reduced need for address state refreshments. From Cisco IOS 12.4(15)T onwards the client can also receive timing information, in addition to the “additional parameters” through DHCPv6. This timing information provides an indication to a host when it should refresh its DHCPv6 configuration data. This behavior (RFC4242) is particularly useful in unstable environments where changes are likely to occur.

240. Which feature allows a device to use a switch port that is configured for half-duplex to access the network?

  • CSMA/CD
  • IGMP
  • port security
  • split horizon

Explanation: Ethernet began as a local area network technology that provided a half-duplex shared channel for stations connected to coaxial cable segments linked with signal repeaters. In this appendix, we take a detailed look at the half-duplex shared-channel mode of operation, and at the CSMA/CD mechanism that makes it work.

In the original half-duplex mode, the CSMA/CD protocol allows a set of stations to compete for access to a shared Ethernet channel in a fair and equitable manner. The protocol’s rules determine the behavior of Ethernet stations, including when they are allowed to transmit a frame onto a shared Ethernet channel, and what to do when a collision occurs. Today, virtually all devices are connected to Ethernet Switch ports over full-duplex media, such as twisted-pair cables. On this type of connection, assuming that both devices can support the full-duplex mode of operation and that Auto-Negotiation (AN) is enabled, the AN protocol will automatically select the highest-performance mode of operation supported by the devices at each end of the link. That will result in full-duplex mode for the vast majority of Ethernet connections with modern interfaces that support full duplex and AN.

241. Which function enables an administrator to route multiple VLANs on a router?

  • IEEE 802 1X
  • HSRP
  • port channel
  • router on a stick

242. Which dynamic routing protocol uses only the hop count to determine the best path to a destination?

  • IGRP
  • RIP
  • EIGRP
  • OSPF

Explanation: Determining the best path involves the evaluation of multiple paths to the same destination network and selecting the optimum or shortest path to reach that network. Whenever multiple paths to the same network exist, each path uses a different exit interface on the router to reach that network.

The best path is selected by a routing protocol based on the value or metric it uses to determine the distance to reach a network. A metric is the quantitative value used to measure the distance to a given network. The best path to a network is the path with the lowest metric.

Dynamic routing protocols typically use their own rules and metrics to build and update routing tables. The routing algorithm generates a value, or a metric, for each path through the network. Metrics can be based on either a single characteristic or several characteristics of a path. Some routing protocols can base route selection on multiple metrics, combining them into a single metric.

The following lists some dynamic protocols and the metrics they use:

Routing Information Protocol (RIP): Hop count
Open Shortest Path First (OSPF): Cisco routers use a cost based on cumulative bandwidth from source to destination
Enhanced Interior Gateway Routing Protocol (EIGRP): Bandwidth, delay, load, reliability

243. What is one requirement for interfaces to run IPv6?

  • An IPv6 address must be configured on the interface.
  • An IPv4 address must be configured.
  • Stateless autoconfiguration must be enabled after enabling IPv6 on the interface.
  • IPv6 must be enabled with the ipv6 enable command in global configuration mode.

Explanation: To use IPv6 on your router, you must, at a minimum, enable the protocol and assign IPv6 addresses to your interfaces.

244. Which destination IP address can a host use to send one message to multiple devices across different subnets?

  • 172.20.1.0
  • 127.0.0.1
  • 192.168.0.119
  • 239.255.0.1

Explanation: Multicast is a networking protocol where one host can send a message to a special multicast IP address and one or more network devices can listen for and receive those messages.
Multicast works by taking advantage of the existing IPv4 networking infrastructure, and it does so in something of a weird fashion. As you read, keep in mind that things are a little confusing because multicast was “shoe-horned” in to an existing technology. For the rest of this article, let’s use the multicast IP address of 239.255.0.1. We’ll not worry about port numbers yet, but make a mental note that they are used in multicast. We’ll discuss that later.

245. Which MTU size can cause a baby giant error?

  • 1500
  • 9216
  • 1600
  • 1518

Explanation:

http://www.cisco.com/c/en/us/support/docs/switches/catalyst-4000-series switches/29805175.html

246. Which entity assigns IPv6 addresses to end users?

  • ICANN
  • APNIC
  • RIR
  • ISPs

Explanation: Before going forward that far it is important to note that like IPv4, the placement of the devices that will be allocated with IPv6 addresses can affect the numbers and the method of assignment. If the IPv6 addresses in question will be used solely for the internal purposes of a business and do not need to be directly routable to the public Internet, then the Unique Local IPv6 range (RFC 4193) and assignment method can be used; these would be the equivalent of RFC 1918 IPv4 private address ranges. If, however, the IPv6 addresses are intended to be directly routable on the public Internet, a range must be assigned (just like with IPv4) by an Internet Service Provider (ISP), or a Regional Internet Registry (RIR) if allocating for an ISP.

As of this writing, the Unique Local address range includes all addresses that fall under the FC00::/7 prefix (they begin with ‘1111110’ in binary), while the Global Unicast address range includes all addresses that fall under the 2000::/3 prefix (they begin with ‘001’ in binary). Global Unicast ranges are divided by a number of different entities, at the top of these entities is Internet Corporation for Assigned Names and Numbers (ICANN) who assigns addresses to the RIR’s (for all regional registries except APNIC), who will in turn assign addresses to ISP’s who will in turn assign addresses to End Users (EU).

247. Which option is the default switch port port-security violation mode?

  • shutdown
  • protect
  • shutdown vlan
  • restrict

Explanation: Shutdown –This mode is the default violation mode; when in this mode, the switch will automatically force the switchport into an error disabled (err-disable) state when a violation occurs. While in this state, the switchport forwards no traffic. The switchport can be brought out of this error disabled state by issuing the errdisable recovery cause CLI command or by disabling and reenabling the switchport.

Shutdown VLAN–This mode mimics the behavior of the shutdown mode but limits the error disabled state the specific violating VLAN.

248. Which statement about the inside interface configuration in a NAT deployment is true?

  • It is defined globally
  • It identifies the location of source addresses for outgoing packets to be translated using access or route maps.
  • It must be configured if static NAT is used
  • It identifies the public IP address that traffic will use to reach the internet.

Explanation: This module describes how to configure Network Address Translation (NAT) for IP address conservation and how to configure inside and outside source addresses. This module also provides information about the benefits of configuring NAT for IP address conservation. NAT enables private IP internetworks that use nonregistered IP addresses to connect to the Internet. NAT operates on a device, usually connecting two networks, and translates the private (not globally unique) addresses in the internal network into legal addresses before packets are forwarded onto another network. NAT can be configured to advertise to the outside world only one address for the entire network. This ability provides additional security by effectively hiding the entire internal network behind that one address. NAT is also used at the enterprise edge to allow internal users access to the Internet and to allow Internet access to internal devices such as mail servers.

249. Which value is indicated by the next hop in a routing table?

  • preference of the route source
  • IP address of the remote router for forwarding the packets
  • how the route was learned
  • exit interface IP address for forwarding the packets

Explanation: From official Odom cisco book is Routes for remote subnets typically list both an outgoing interface and next-hop router IP address. Routes for subnets that connect directly to the router list only the outgoing interface, because packets to these destinations do not need to be sent to another router.

250. Which option is a valid hostname for a switch?

  • 5witch-Cisco
  • Switch-Cisco!
  • 5witchCisco
  • SwitchCisc0

Explanation: Hostnames can’t start with a number, and can’t have special characters (bangs/exclamation) (but can have a dash).

Astarts with a number.
Bhas a bang at the end.
Cstarts with a number.
Only D is correct.

251. Which component of the routing table ranks routing protocols according to their preferences?

  • administrative distance
  • next hop
  • metric
  • routing protocol code

Explanation: Administrative distance – This is the measure of trustworthiness of the source of the route. If a router learns about a destination from more than one routing protocol, administrative distance is compared and the preference is given to the routes with lower administrative distance. In other words, it is the believability of the source of the route.

252. Which statement about unicast frame forwarding on a switch is true?

  • The TCAM table stores destination MAC addresses
  • If the destination MAC address is unknown, the frame is flooded to every port that is configured in the same VLAN except on the port that it was received on.
  • The CAM table is used to determine whether traffic is permitted or denied on a switch
  • The source address is used to determine the switch port to which a frame is forwarded

253. Which statement about native VLAN traffic is true?

  • Cisco Discovery Protocol traffic travels on the native VLAN by default
  • Traffic on the native VLAN is tagged with 1 by default
  • Control plane traffic is blocked on the native VLAN.
  • The native VLAN is typically disabled for security reasons

Explanation: The native VLAN is the VLAN that is configured for packets that don’t have a tag. The default native VLAN on all Cisco Switches is VLAN 1. It is always enabled by default. These settings can all be changed: That is: you can designate a different VLAN as the native VLAN, disable VLAN 1, etc. Knowing that, we can eliminate D) as the correct answer because it is enabled by default. We can also eliminate B) because Native VLAN packets don’t get tags by default (you can change this). Finally, Control Plane traffic is never blocked on Native VLAN 1, and even if you change the Native VLAN, the control plane traffic still comes across VLAN 1.

254. Which route source code represents the routing protocol with a default administrative distance of 90 in the routing table?

  • S
  • E
  • D
  • R
  • O

Explanation:

SStatic
EEGP
DEIGRP
RRIP
OOSPF
Default Administrative distance of EIGRP protocol is 90 then answer is C.

Default Distance Value Table This table lists the administrative distance default values of the protocols that Cisco supports: Route Source

Default Distance Values
Connected interface
Static route
Enhanced Interior Gateway Routing Protocol (EIGRP) summary route External Border Gateway Protocol (BGP)
Internal EIGRP
IGRP
OSPF
Intermediate System-to-Intermediate System (IS-IS) Routing Information Protocol (RIP)
Exterior Gateway Protocol (EGP)
On Demand Routing (ODR)
External EIGRP
Internal BGP

255. Refer to the exhibit. Which statement describes the effect of this configuration?

Router# configure terminal 
Router (config)# vlan 10 
Router (config-vlan)# do show vlan
  • The VLAN 10 VTP configuration is displayed.
  • VLAN 10 spanning-tree output is displayed.
  • The VLAN 10 configuration is saved when the router exits VLAN configuration mode.
  • VLAN 10 is added to the VLAN database.

Explanation: With the configuration above, when we type “do show vlan” we would not see VLAN 10 in the VLAN database because it has not been created yet. VLAN 10 is only created when we exits VLAN configuration mode (with “exit” command).

256. When enabled, which feature prevents routing protocols from sending hello messages on an interface’?

  • virtual links
  • passive-interface
  • directed neighbors
  • OSPF areas

Explanation: You can use the passive-interface command in order to control the advertisement of routing information. The command enables the suppression of routing updates over some interfaces while it allows updates to be exchanged normally over other interfaces. With most routing protocols, the passive-interface command restricts outgoing advertisements only.

But, when used with Enhanced Interior Gateway Routing Protocol (EIGRP), the effect is slightly different. This document demonstrates that use of the passive-interface command in EIGRP suppresses the exchange of hello packets between two routers, which results in the loss of their neighbor relationship. This stops not only routing updates from being advertised, but it also suppresses incoming routing updates. This document also discusses the configuration required in order to allow the suppression of outgoing routing updates, while it also allows incoming routing updates to be learned normally from the neighbor.

257. Which device allows users to connect to the network using a single or double radio?

  • access point
  • switch
  • wireless controller
  • firewall

258. Two hosts are attached to a switch with the default configuration. Which statement about the configuration is true?

  • IP routing must be enabled to allow the two hosts to communicate.
  • The two hosts are in the same broadcast domain
  • The switch must be configured with a VLAN to allow the two hosts to communicate.
  • Port security prevents the hosts from connecting to the switch.

Explanation: http://www.cisco.com/c/en/us/support/docs/lan-switching/inter-vlan-routing/41860-howto-L3intervlanrouting.html

259. By default, how many MAC addresses are permitted to be learned on a switch port with port security enabled?

  • 8
  • 2
  • 1
  • 0

260. Which statement about a router on a stick is true?

  • Its date plane router traffic for a single VI AN over two or more switches
  • It uses multiple subinterfaces of a single interface to encapsulate traffic for different VLANS on the same subnet.
  • It requires the native VLAN to be disabled.
  • It uses multiple subinterfaces of a single interface to encapsulate traffic for different VLANs.

Explanation: https://www.freeccnaworkbook.com/workbooks/ccna/configuring-inter-vlan-routing-router-on-astick

261. Which network topology allows all traffic to flow through a central hub?

  • bus
  • star
  • mesh
  • ring

Explanation: Star topology is the most popular topology for the network which allows all traffic to flow through a central device.

262. Which NAT type is used to translate a single inside address to a single outside address?

  • dynamic NAT
  • NAT overload
  • РАТ
  • static NAT

Explanation: Network address translation (NAT) is the process of modifying IP address information in IP packet headers while in transit across a traffic routing device.
There are two different types of NAT:
NAT
PAT

263. What is the default lease time for a DHCP binding?

  • 24 hours
  • 12 hours
  • 48 hours
  • 36 hours

Explanation: By default, each IP address assigned by a DHCP Server comes with a one-day lease, which is the amount of time that the address is valid. To change the lease value for an IP address, use the following command in DHCP pool configuration mode:

264. Which RFC was created to alleviate the depletion of IPv4 public addresses?

  • RFC 4193
  • RFC 1519
  • RFC 1518
  • RFC 1918

Explanation:
RFC 4193: Unique Local IPv6 Unicast Addresses.
RFC 1519: Classless Inter-Domain Routing (CIDR): an Address Assignment and Aggregation Strategy.
RFC 1518: An Architecture for IP Address Allocation with CIDR.
RFC 1918. Address Allocation for Private Internets.

265. Configuration of which option is required on a Cisco switch for the Cisco IP phone to work?

  • PortFast on the interface
  • the interface as an access port to allow the voice VLAN ID
  • a voice VLAN ID in interface and global configuration mode
  • Cisco Discovery Protocol in global configuration mode

Explanation: Configure the Switch Port to Carry Both Voice and Data Traffic When you connect an IP phone to a switch using a trunk link, it can cause high CPU utilization in the switches. As all the VLANs for a particular interface are trunked to the phone, it increases the number of STP instances the switch has to manage. This increases the CPU utilization. Trunking also causes unnecessary broadcast / multicast/ unknown unicast traffic to hit the phone link. In order to avoid this, remove the trunk configuration and keep the voice and access VLAN configured along with Quality of Service (QoS). Technically, it is still a trunk, but it is called a Multi-VLAN Access Port (MVAP). Because voice and data traffic can travel through the same port, you should specify a different VLAN for each type of traffic. You can configure a switch port to forward voice and data traffic on different VLANs. Configure IP phone ports with a voice VLAN configuration. This configuration creates a pseudo trunk, but does not require you to manually prune the unnecessary VLANs. The voice VLAN feature enables access ports to carry IP voice traffic from an IP phone. The voice VLAN feature is disabled by default. The Port Fast feature is automatically enabled when voice VLAN is configured. When you disable voice VLAN, the Port Fast feature is not automatically disabled.

266. Which statement describes the effect of the overload keyword in the ip nat inside source list 90 interface ethernet 0/0 overload command?

  • Addresses that match address list inside are translated to the IP address of the Ethernet 0/0 interface.
  • Hosts that match access inside are translated to an address m the Ethernet 0/0 network.
  • Hosts on the Ethernet 0/0 LAN are translated to the address pool in access list 90.
  • Addresses that match access list 90 are translated through PAT to the IP address of the Ethernet 0/0 interface

267. Which statement describes the effect of the copy run start command on a router in enable mode?

  • The running configuration of the router is saved to NVRAM and used during the boot process.
  • The router reboots and loads the last saved running configuration.
  • A copy of the running configuration of the router is sent by FTP to a designated server.
  • A new running configuration is loaded from flash memory to the router.

268. After you configure a default route to the Internet on a router, the route is missing from the routing table. Which option describes a possible reason for the problem?

  • The next-hop address is unreachable.
  • The default route was configured on a passive interface.
  • Dynamic routing is disabled.
  • Cisco Discovery Protocol is disabled on the interface used to reach the next hop.

269. You have configured the host computers on a campus LAN to receive their DHCP addresses form the local router to be able to browse their corporate site. Which statement about the network environment is true?

  • It supports a DNS server for use by DHCP clients.
  • Two host computers may be assigned the same IP address.
  • The DNS server must be configured manually on each host.
  • The domain name must be configured locally on each host computer.

Explanation: The local router in this case is called a DHCP server. The main purpose of a DHCP server is to assign IP addresses to the clients. Besides that, a DHCP server can also specify the IP address of the DNS server and specify the domain name for the clients. For more information about configuring a DHCP server, please read: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dhcp/configuration/12-4t/dhcp-12-4tbook/config-dhcp-server.html

270. Which protocol verifies connectivity between two switches that are configured with IP addresses in the same network?

  • ICMP
  • STP
  • VTP
  • HSRP

271. On which OSI layer does a VLAN operate?

  • Layer 1
  • Layer 2
  • Layer 3
  • Layer 4

272. Which NAT command can be applied to an interface?

  • ip nat inside
  • ip nat inside test access-list-number pool pool-name
  • ip nat inside source static 10.10.10.0 10.10.10.50
  • ip nat pool test 10.10.10.0 10.10.10.50 255.255.255.0

273. Which technique can you use to route IPv6 traffic over an IPv4 infrastructure?

  • NAT
  • 6to4 tunneling
  • L2TPv3
  • dual-stack

274. Which Ethernet interface command is present when you boot a new Cisco router for the first time?

  • speed 100
  • shutdown
  • ip address 192.168.1.1 255.255.255.0
  • duplex half

275. Which table displays the MAC addresses that are learned on a switch?

  • FIB
  • ARP
  • TCAM
  • CAM

Explanation: The table is built by recording the source address and inbound port of all frames. As frames arrive on switch ports, the source MAC addresses are learned and recorded in the CAM table. The port of arrival and the VLAN are both recorded in the table, along with a timestamp. If a MAC address learned on one switch port has moved to a different port, the MAC address and timestamp are recorded for the most recent arrival port. Then, the previous entry is deleted. If a MAC address is found already present in the table for the correct arrival port, only its timestamp is updated.

276. Which statement is a Cisco best practice for switch port security?

  • Vacant switch ports must be shut down.
  • Empty ports must be enabled in VLAN 1.
  • VLAN 1 must be configured as the native VLAN.
  • Err-disabled ports must be configured to automatically re-enable.

277. Which NTP concept indicates the distance between a device and the reliable time source?

  • clock offset
  • stratum
  • reference
  • dispersion

278. Which command displays the number of times that an individual router translated an inside address to an outside address?

  • show ip protocol
  • show ip nat translation
  • show counters
  • show ip route
  • show ip nat statistics

279. Which set of conditions comprises a successful ping attempt between two connected routers configured with IP addresses on the same subnet?

  • The destination host receives an echo reply from the source host within one second and the source host receives an echo request from the destination host.
  • The destination host receives an echo request from the source host within one second.
  • The destination host receives an echo reply from the source host within one second and the source host receives an echo reply from the destination host within two seconds
  • The destination host receives an echo request from the source host and the source host receives an echo request from the destination host within one second.
  • The destination host receives an echo request from the source host and the source host receives an echo reply from the destination host within two seconds.

280. What happens when the cable is too long?

  • Baby Giant
  • Late collision

281. Which two VLANs are reserved for system use only? (Choose two)

  • 1
  • 4095
  • 4096
  • 0
  • 1001

Explanation: The VLANs 0 and 4095 are reserved by the IEEE 802.1Q standard and you cannot create, delete, or modify them so they are the correct answers.
Note:
+ VLAN 0 and 4095 are reserved for system use only. You cannot see or use these VLANs.
+ VLAN 1 and VLANs 1002-1005 are default VLANs. Default VLANs are created automatically and cannot be configured or deleted by users.
+ VLAN 2 to 1001 are normal VLANs. You can create, use and delete them.
+ VLAN 1002 to 1005 are normal VLANs too but Cisco reserved for FDDI an Token Ring.

282. What is the requirement of configuring 6to4 tunnelling on two routers?

  • Both ipv6 and ipv4 must be configured
  • Only IPv6
  • Only IPv4

283. Which name describes an IPV6 host-enable tunneling technique that uses IPV4 UDP,does not require dedicated gateway tunnels, and can pass through existing IPV4 NAT gateways?

  • dual stack XX
  • dynamic
  • Teredo
  • Manual 6to4

284. Which sequence begins a unique local IPv6 address in binary notation?

  • 00000000
  • 1111110
  • 1111100
  • 1111111

285. Which statement about 6to4 tunneling is true?

  • One tunnel endpoint must be configured with IPv4 only
  • It establishes a point-to-point tunnel
  • Both tunnel endpoints must be configured with IPv4 only
  • Both tunnel endpoints must support IPv4 and IPv6

286. What is true about ipv6 unique local addresses:

  • Global id
  • Public routable
  • Summarization
  • Unique prefix

287. How do you bypass password on cisco device?

  • Change the configuration register to 0x2142. With this setting when that router reboots, it bypasses the startup-config and no password is required.

288. How many primary ipv4 addresses can be assigned on router interface ?

  • 0
  • 1
  • 4
  • Unlimited

289. Which command is used to build DHCP pool?

  • ipdhcp conflict
  • ipdhcp-server pool DHCP
  • ipdhcp pool DHCP
  • ipdhcp-client pool DHCP

290. What occurs when an Ethernet cable is too long?

  • Giants
  • Runts
  • late collisions
  • interface resets

291. You are configuring dynamic NAT on your Cisco IOS router. Which command is used to verify the interfaces that are being used as the outside interface and the inside interface?

  • show interfaces
  • show ip route
  • show ipnat translations
  • show ip interface brief
  • show ip interface
  • show ipnat statistics

292. What disables CEF?

  • RIB
  • IPv6
  • Ping
  • Disable Logging

293. What is the default configuration of a Cisco switch?

  • No default gateway assigned
  • System name is Cisco

294. When you configure router# ipnat pool 10.10.10.1 10.10.10.20 255.255.255.0

  • nat pool
  • dynamicnat
  • nat translation
  • dhcp pool

295. Which technology allows a large number of private IP addresses to be represented by a smaller number of public IP addresses?

  • NAT
  • NTP
  • RFC 1631
  • RFC 1918

296. Which command can you enter to verify that a 128-bit address is live and responding?

  • traceroute
  • telnet
  • ping
  • ping ipv6

297. Refer to the exhibit. You have discovered that computers on the 192 168 10 0/24 network can ping their default gateway, but they cannot connect to any resources on a remote network. Which reason for the problem is most likely true?

  • The 192.168.12 0/24 network is missing from OSPF
  • The OSPF process ID is incorrect
  • The OSPF area number is incorrect.
  • An ARP table entry is missing for 192.168.10.0.
  • A VLAN number is incorrect for 192.168.10.0.

298. If three devices are plugged into one port on a switch and two devices are plugged into a different port, how many collision domains are on the switch?

  • 2
  • 4
  • 5
  • 6

99. Which three commands must you enter to create a trunk that allows VLAN 20? (Choose three)

  • Switch(config-if)#switchport mode dynamic auto
  • Switch(config-if)#switchport mode trunk
  • Switch(config-if)#switchport trunk allowed vlan 20
  • Switch(config-if)#switchport mode dynamic desirable
  • Switch(config-if)#switchport trunk encapsulation dotlq
  • Switch(config-if)#switchport trunk native vlan 20

300. Which three options are types of Layer 2 network attack? (Choose three.)

  • ARP attacks
  • brute force attacks
  • spoofing attacks
  • DDOS attacks
  • VLAN hopping
  • botnet attacks

301. How does a router handle an incoming packet whose destination network is missing from the Routing table?

  • it discards the packet.
  • it broadcasts the packet to each network on the router.
  • it routes the packet to the default route.
  • it broadcasts the packet to each interface on the router.

302. Which feature facilitates the tagging of frames on a specific VLAN?

  • Routing
  • hairpinning
  • switching
  • encapsulation

303. When you troubleshoot an IPv4 connectivity issue on a router, which three router configuration checks you must perform?

  • Verify that the router interface IP address IP address is correct.
  • Verify that the DNS is configured correctly.
  • Verify that the router and the host use the same subnet mask.
  • Verify that the router firmware is up-to-date.
  • Verify that a default route is configured.
  • Verify that the route appears in the Routing table

304. Which two statements about unique local IPv6 addresses are true?

  • They are identical to IPv4 private addresses.
  • They are defined by RFC 1884.
  • They use the prefix FECO::/10
  • They use the prefix FC00::/7
  • They can be routed on the IPv6 global internet.

305. Which header field is new in IPv6?

  • Hop Limit
  • Flow Label
  • Version
  • Traffic Class

306. Which feature automatically disables CEF when it is enabled?

  • RIB
  • ACL logging
  • multicast
  • IP redirects

Explanation: ACL Logging means to use the “log” or “log-input” parameters at the end of the ACL statements. For example: “access-list 100 deny icmp any any echo reply log-input”. In either situation, remember that using either of these two parameters disables CEF switching, which seriously impacts the performance of the router.

307. Which NAT term is defined as a group of addresses available for NAT use?

  • one-way NAT
  • static NAT
  • dynamic NAT
  • NAT pool

308. Which statement about NTP is true?

  • each device is enabled as server by default
  • the default authentication key number is 1
  • the default stratum number is 5
  • the default source of a ntp message is the interface connected to the next-hop for server peer address

309. Which information is used to install the best route to a destination in IP routing table?

  • the tunnel ID
  • the interface number
  • the prefix length
  • the autonomous system

310. Which port-security feature allows a switch to learn MAC addresses dynamically and add them to the running config?

  • Stick
  • Other option

311. Which statement about dhcp address pools is true?

  • the domain name of the dhcp pool is specified in the global configuration of the router
  • Other option

312. If a router has 3 hosts connected in one port and two other hosts connected in another port, how many broadcast domains are present on the router?

  • 5
  • 2
  • 3
  • 4

313. What does split horizon prevent?

  • routing loops, link state
  • routing loops, distance vector
  • switching loops, STP
  • switching loops, VTP

314. Which value to use in HSRP protocol election process?

  • interface
  • virtual IP address
  • priority
  • router ID

315. Which of the following is needed to be enable back the role of active in HSRP?

  • preempt
  • priority
  • Other option

316. Which command is used to show the interface status of a router?

  • show interface status
  • show ip interface brief
  • show ip route
  • show interface

317. Which of the following privilege level is the most secured?

  • Level 0
  • Level 1
  • Level 15
  • Level 16

318. Which IPV6 feature is supported in IPV4 but is not commonly used?

  • unicast
  • multicast
  • anycast
  • broadcast

319. Which range represents the standard access list?

  • 99
  • 150
  • 299
  • 2000

320. What to do when the router password was forgotten?

  • use default password cisco to reset
  • access router physically
  • use ssl/vpn
  • Type confreg 0x2142 at the rommon 1

321. What 8-bit field exists in IP packet for QoS?

  • Tos Field
  • DSCP
  • IP Precedence
  • Cos

322. What feature uses a random time to re-sent a frame?

  • CSMA/CA
  • CSMA/CD
  • Other option

323. Which mode is compatible with Trunk, Access, and desirable ports?

  • Trunk Ports
  • Access Ports
  • Dynamic Auto
  • Dynamic Desirable

324. If you configure syslog messages without specifying the logging trap level, which log messages will the router send?

  • 0-4
  • 0-5
  • 0-6
  • 0-2
  • 0-1

Related Articles

guest
57 Comments
Newest
Oldest Most Voted
Inline Feedbacks
View all comments