Networking Devices and Initial Configuration Module 4 - 6 Checkpoint Test Online

Hint

In order to send data to HostA, ServerB will generate a packet that contains the IP address of the destination device on the remote network and a frame that contains the MAC address of the default gateway device on the local network.

Hint

When another switch or a hub is connected to a switch port then frames could be received from the multiple nodes connected to the other switch or the hub. This will result in the MAC address for each of those multiple nodes to be recorded in the MAC address table against that one port. When a router is connected to a switch port, only the MAC address of the router interface would be recorded against the switch port. ARP broadcasts are used to associate MAC addresses with IP addresses and such broadcasts would not directly result in multiple MAC addresses being recorded against a single switch port. Configuring the switch to perform Layer 3 switching will not result in multiple MAC addresses being recorded against a single switch port. The ARP table associated with the Layer 3 switch port may contain multiple IP address to MAC address mappings but this is to enable the correct framing of Layer 3 packets, not the Layer 2 frame switching function.

Hint

Issuing the command ipconfig /all from the PC0 command prompt displays the IPv4 address and MAC address. When the IPv4 address 10.1.1.5 is pinged from PC0, the switch stores the source MAC address (from PC0) along with the port to which PC0 is connected. When the destination reply is received, the switch takes the destination MAC address and compares to MAC addresses stored in the MAC address table. Issuing the show mac-address-table on the PC0 Terminal application displays two dynamic MAC address entries. The MAC address and port entry that does not belong to PC0 must be the MAC address and port of the destination with the IPv4 address 10.1.1.5.

Hint

To maintain the MAC address table, the switch uses the source MAC address of the incoming packets and the port that the packets enter. The destination address is used to select the outgoing port.

Hint

The MAC address of PC3 is not present in the MAC table of the switch. Because the switch does not know where to send the frame that is addressed to PC3, it will forward the frame to all the switch ports, except for port 4, which is the incoming port.

Hint

Ethernet standards define a frame size with a minimum of 64 bytes and a maximum of 1518 bytes including fields of destination MAC address, source MAC, Length/Type, data payload, and FCS.

Hint

Switch S1 builds a MAC address table based on the source MAC address in the frame and the port upon which the frame enters the switch. The PC2 MAC address will be associated with port FA0/2. Because port FA0/1 of switch S1 connects with another switch, port FA0/1 will receive frames from multiple different devices. The MAC address table on switch S1 will therefore contain MAC addresses associated with each of the sending PCs.

Hint

The network layer is primarily concerned with passing data from a source to a destination on another network. IP addresses supply unique identifiers for the source and destination. The network layer provides connectionless, best-effort delivery. Devices rely on higher layers to supply services to processes.

Hint

Differentiated services (DiffServ) is an IPv4 header field that is used to define the priority of each packet. The first 6 bits identify the value that is used by the QoS mechanism, and the last 2 bits identify the value that can be used to avoid packet dropping during network congestion. Traffic class is an IPv6 header field that is equivalent to the IPv4 differentiated services (DiffServ) field. Flow label is also an IPv6 header field that can be used to tell routers and switches to keep the same path for the packet flow to avoid packet reordering. Flags is an IPv4 header field that identifies how the packet is fragmented.

Hint

ICMPv6, like IPv4, sends a Time Exceeded message if the router cannot forward an IPv6 packet because the packet has expired. However, the IPv6 packet does not have a TTL field. Instead, it uses the Hop Limit field to determine if the packet has expired.

Hint

NAT for IPv6 is a temporary measure to aid in the move from IPv4 to IPv6. NAT64 is replacing NAT-PT. Dual stack is a method for running IPv4 and IPv6 on the same network.

Hint

Optional Layer 3 information about fragmentation, security, and mobility is carried inside of extension headers in an IPv6 packet. The next header field of the IPv6 header acts as a pointer to these optional extension headers if they are present.

Hint

Options matched to the correct selection.

IPv4	IPv6
12 basic header fields	128-bit address space
20 octets header	40 octets header
32-bit address space	8 header fields

Hint

The IPv6 simplified header offers several advantages over IPv4: · Better routing efficiency and efficient packet handling for performance and forwarding-rate scalability · No requirement for processing checksums · Simplified and more efficient extension header mechanisms (as opposed to the IPv4 Options field) · A Flow Label field for per-flow processing with no need to open the transport inner packet to identify the various traffic flows

Hint

The subnet mask shows which part of the IP address is the network number. Because all the devices have a subnet mask of 255.255.255.0, the first three sets of numbers in each IP address indicate the network number. The server and laptop C both have network numbers of 192.168.3.0.

Hint

ANDing allows us to identify the network address from the IP address and the network mask.

Hint

The subnet mask of 255.255.255.224 identifies the network of 192.168.44.128. The usable range for the network is 192.168.44.129 through 192.168.44.158. The default gateway address of 192.168.44.161 exists on a separate network from the PC it is configured on.

Hint

When network 192.168.100.0 /24 is subnetted into 16 subnets, each subnet will have a new network mask of 255.255.255.240. This new mask will leave four bits of the address available for hosts. Four host bits yield 16 host addresses. However, two of those addresses are reserved, the lowest for the subnet and the highest for the subnet broadcast. This leaves 14 addresses for host configuration.

Hint

/28 represents the number of consecutive 1s in the subnet mask. 24 1s makes the 255.255.255 part of the subnet mask. The last 4 1s in the mask is where it gets a little tricky. Add the values that these 4 1s represent to get the last octet of the mask: 128 + 64 + 32 + 16 = 240. /28 = 255.255.255.240

Hint

The subnet mask determines which part of the IP address is the network number. Because the subnet mask is 255.255.255.0, the first three sets of numbers in each IPv4 address indicate the network number. IPv4 addresses with the same network number are considered in the same local network.

Hint

Hosts 172.16.100.4/23 and 172.16.101.199/23 both exist in network 172.16.100.0/23. This network includes all addresses from 172.16.100.1 through 172.16.101.255.