Checkpoint Exam: Cisco Devices and Troubleshooting Network Issues: Network Addressing and Basic Troubleshooting Module 7 – 8 Checkpoint Exam Answers (NABT)
1. After several configuration changes are made to a router, the copy running-configuration startup-configuration command is issued. Where will the changes be stored?
- NVRAM
- RAM
- flash
- ROM
Explanation: When changes are made to the running-config file, it should be saved to NVRAM as the startup configuration file in case the router is restarted or loses power. The following command saves the configuration to NVRAM:
copy running-config startup-config
2. A technician is troubleshooting a network device and suspects there might be a duplex mismatch. What could cause a duplex mismatch?
- interface misconfiguration
- data corruption
- interconnection of unlike devices
- auto-MDIX detection failure
Explanation: Duplex mismatches are typically caused by a misconfigured interface or, in rare instances, by a failed autonegotiation. Duplex mismatches may be difficult to troubleshoot because the communication between devices still occurs.
3. Which statement describes the half-duplex mode of data transmission?
- Data that is transmitted over the network can only flow in one direction.
- Data that is transmitted over the network flows in both directions at the same time.
- Data that is transmitted over the network flows in one direction to many different destinations simultaneously.
- Data that is transmitted over the network flows in one direction at a time.
Explanation: The data that is transmitted over the network can flow using one of three modes:
Simplex – Data can only flow in one direction.
Half-duplex – Data flows in one direction at a time.
Full-duplex – Data flows in both directions at the same time.
4. What is the first action in the boot sequence when a switch is powered on?
- load boot loader software
- load a power-on self-test program
- load the default Cisco IOS software
- low-level CPU initialization
Explanation: The first action to take place when a switch is powered on is the POST or power-on self-test. POST performs tests on the CPU, memory, and flash in preparation for loading the boot loader.
5. Match the command to the function.
Explanation: Place the options in the following order:
| ping | tests end-to-end connectivity between hosts |
| netstat | displays network connections |
| tracert | displays the route that is taken to the destination |
| ipconfig | displays IP settings on host |
| nslookup | asks the name server for information on the destination domain |
6. Which two statements are true about half-duplex and full-duplex communications? (Choose two.)
- Half-duplex is supported on Gigabit Ethernet links.
- Full duplex enables transmission in only one direction at a time.
- Half duplex links do not experience collisions.
- Full duplex allows both ends to transmit and receive simultaneously.
- Full duplex increases the effective bandwidth.
Explanation: Full-duplex communication allows both ends to transmit and receive simultaneously, offering 100 percent efficiency in both directions for a 200 percent potential use of stated bandwidth. Half-duplex communication is unidirectional, or one direction at a time. Gigabit Ethernet and 10 Gb/s NICs require full duplex to operate, and do not support half-duplex operation.
7. Which two access methods can be used for in-band configuration of a Cisco device? (Choose two.)
- CLI
- AUX
- console
- SSH
- Telnet
Explanation: In-band configuration requires at least one interface to be active and configured with an IP address to allow for Telnet and SSH connections. AUX and console connections are out-of-band connection methods that do not require any networking services to be configured. CLI is used to configure devices, but does not provide access.
8. What is required for a network administrator to perform out-of-band management tasks on a Cisco device?
- a computer directly connected to the console port of the device
- an active network connection available to the device
- a valid IP address configured on VLAN 1
- SSH enabled and functional on the device
Explanation: With out-of-band management, the only requirement is to have a computer directly connected to the console port of the device. This is the primary method to configure a new device because no network connection or prior configurations on the device is required.
9. A network technician is attempting to connect an older device to a FastEthernet port on a Cisco switch. The technician has manually configured the device to full-duplex mode in order to enhance the network performance of the device. However, when the device is attached to the network, performance degrades and excessive collisions are detected on the switch. What is the likely cause of this problem?
- The host is configured in a different subnet from the subnet of the switch.
- There is a duplex mismatch between the device and switch port.
- The switch port is running at a different speed from the speed of the device NIC.
- The host has been configured with a default gateway that is different from that of the switch.
Explanation: Duplex mismatch is one of the most common causes of performance issues on 10/100 Mbps Ethernet links. It occurs when one port on the link operates at half-duplex while the other port operates at full-duplex
10. A router boots and enters setup mode. What is the reason for this?
- The configuration file is missing from NVRAM.
- The POST process has detected hardware failure.
- Cisco IOS is missing from flash memory.
- The IOS image is corrupt.
Explanation: If a router cannot locate the startup-config file in NVRAM it will enter setup mode to allow the configuration to be entered from the console device.
11. Local workstations are unable to access web pages located on the www.cisco.com web server. Pings from the workstations to the server using the ping www.cisco.com command are successful. What settings should the administrator check to determine the cause of the problem?
- firewall settings
- DNS server settings
- IP address settings
- MAC address settings
Explanation: If Layers 1 through 3 appear to be operating successfully and the devices can ping the web server, the firewall settings should be checked to determine if the web traffic to the server is permitted.
12. Users in a recently installed wireless network are complaining of slow data transfer and frequent loss of connectivity. The technician checks that the wireless security is correctly implemented, and there is no evidence of unauthorized users on the network. Which two problems might the technician suspect? (Choose two.)
- The wireless signal is too weak.
- The DHCP server is faulty.
- The antenna on the access point is too powerful.
- The network passwords need to be reissued to the users.
- There is interference from outside sources.
Explanation: Normally, the closer a wireless NIC is to an access point, the faster the connectivity. This problem does not require the network password to be reissued. The combination of the low bandwidth and the intermittent connectivity is pointing towards a weak signal or interference from outside sources.
13. Refer to the exhibit. The command output is from a wireless DHCP host connected to a Linksys integrated router. What can be determined from the output?
- A new wireless NIC needs to be installed.
- There is a DNS problem.
- The DHCP configuration needs to be checked.
- The connection to the SSID needs to be verified.
- An incorrect cable is being used between the host and the router.
Explanation: The default gateway IP address must be in the same network as the host in order for the host and router to communicate with each other. Because this is a DHCP client, the IP configuration is provided by the DHCP. Thus the DHCP configuration should be checked and corrected.
14. A network technician enters the command ipconfig /release followed by ipconfig /renew in order to ensure that the DHCP IP configuration on a workstation is updated. However, the workstation does not receive a valid IP configuration for the network. Which two problems may exist on the network? (Choose two.)
- There is no network connectivity to the DHCP server.
- There is a DHCP server issue.
- The DHCP lease time is misconfigured.
- The ipconfig /all command must be issued to restore all IP configurations.
- The gateway router address needs to be updated.
Explanation: The command ipconfig /release will release the current DHCP binding. Ipconfig /renew will request fresh configuration information from the DHCP server. After these two commands are issued, if the workstation is unable to obtain a valid IP configuration from the DHCP server, it could be that there is no network connectivity or the DHCP server is not operational.
15. Which step in the troubleshooting process describes steps that were taken and repair processes that were performed previously?
- documentation of the problem and its solution
- preparation of a plan of action
- identification of the problem
- implementation of the solution
Explanation: Documentation of all steps taken in troubleshooting, even the ones that did not solve the issue, is a valuable reference should the same or similar problem occur again. Good documentation can save hours of trying to remember how a problem was fixed in the past.
16. A medium-sized company uses APs, WLCs, and laptops for employee workstations. An employee reports the inability to connect to the Internet. A technician verifies that other workstations can successfully connect to the Internet. What are two possible reasons for the problem? (Choose two.)
- The workstation is out of range.
- A default gateway is improperly configured on the AP.
- A bad cable exists between the client and the WLC.
- The wireless client is not configured for DHCP.
- The AP does not have power.
Explanation: When troubleshooting a single wireless client, take into consideration all the things a client needs to join and use the network including the following:
– The client must be within RF range of an AP and requests to authenticate.
– The client authenticates.
– The client requests and receives an IP address.
17. A user has taken a personal laptop to work. The laptop is unable to discover the name of the office wireless network. What are two potential causes of this problem? (Choose two.)
- The wireless router is set to mixed mode.
- The laptop has not received an IP address from the wireless router.
- The network does not support the wireless protocol in use by the laptop.
- The wireless router is not broadcasting the SSID.
- The laptop must be configured with the office workgroup name.
Explanation: The laptop could be using an older NIC that uses a protocol not supported by the network. This would be especially likely if the wireless router was not configured in mixed mode. In addition, the wireless router could have SSID broadcasting deactivated. In either case, the computer would not be able to discover the network name. An IP address or workgroup configuration is not required to see the network name.
18. Refer to the exhibit. A network engineer is troubleshooting why PC1 cannot communicate with hosts in other networks. What is the problem?
- The subnet mask that is configured on PC1 is the same as the mask that is configured on the router R1 interface.
- The IP address that is configured on PC1 is in a different network than the gateway address on router R1.
- A default route has not been configured on router R1.
- A default gateway IP address of 10.20.1.1 needs to be configured on PC1.
Explanation: For PC1 to be able to communicate with hosts on the other networks, it needs to have an IP address in the same network as the gateway to which it is connected. Its current address of 10.100.1.10/16 is not within the 10.10.0.0/16 network of the gateway interface on R1 (address 10.10.1.1/16).
19. Which statement describes the ping and tracert commands?
- Ping shows whether the transmission is successful; tracert does not.
- Tracert shows each hop, while ping shows a destination reply only.
- Both ping and tracert can show results in a graphical display.
- Tracert uses IP addresses; ping does not.
Explanation: The ping utility tests end-to-end connectivity between the two hosts. However, if the message does not reach the destination, there is no way to determine where the problem is located. On the other hand, the traceroute utility (tracert in Windows) traces the route a message takes from its source to the destination. Traceroute displays each hop along the way and the time it takes for the message to get to that network and back.
20. A laptop cannot connect to a wireless access point. Which two troubleshooting steps should be taken first? (Choose two.)
- Ensure that the wireless SSID is chosen.
- Ensure that the correct network media is selected.
- Ensure that the NIC is configured for the proper frequency.
- Ensure that the laptop antenna is attached.
- Ensure that the wireless NIC is enabled.
Explanation: A wireless laptop normally does not have an antenna attached unless a repair has recently been implemented. If the wireless NIC is enabled, the correct media, radio, will be used. When the NIC detects an access point, the correct frequency is automatically used.
21. What characteristic of store-and-forward switching is important when a network supports voice over IP (VoIP)?
- It stores only the first 64 bytes of the frame.
- It is required for QoS analysis in converged networks to prioritize traffic.
- It offers a lower level of latency compared to the fragment-free switching method.
- It computes the CRC based on the first 64 bits of the frame.
Explanation: The store-and-forward frame forwarding method receives the entire frame and computes the CRC, based on the number of bits (1s) in the frame, to determine whether the received frame has an error. This method is required for QoS analysis on converged networks where frame classification for traffic prioritization is necessary.
22. What type of Ethernet cable would be used to connect one switch to another switch when neither switch supports the auto-MDIX feature?
- straight-through
- rollover
- crossover
- coaxial
Explanation: A straight-through cable can be used to connect a computer or a router to a switch. A rollover cable can be used to access a router or switch console line. A coaxial cable is not used any longer in Ethernet networks, but can be found in video connections. A crossover cable can be used to connect a switch to a switch, a computer to a computer, and a router to a router.
23. Following default settings, what is the next step in the router boot sequence after the IOS loads from flash?
- Load the running-config file from RAM.
- Load the bootstrap program from ROM.
- Perform the POST routine.
- Locate and load the startup-config file from NVRAM.
Explanation: There are three major steps to the router boot sequence:
- Perform Power-On-Self-Test (POST)
- Load the IOS from Flash or TFTP server
- Load the startup configuration file from NVRAM