Chapter 4: Quiz – Troubleshooting EIGRP for IPv4 (Answers) CCNPv8 ENARSI

1. Refer to the exhibit. Which two conclusions can be derived from the output? (Choose two.)

Chapter 4: Quiz - Troubleshooting EIGRP for IPv4 (Answers) CCNPv8 ENARSI 10

  • There is one feasible successor to network 192.168.1.8/30.
  • The network 192.168.10.8/30 can be reached through 192.168.11.1.
  • The reported distance to network 192.168.1.0/24 is 41024256.
  • The neighbor 172.16.6.1 meets the feasibility condition to reach the 192.168.1.0/24 network.
  • Router R1 has two successors to the 172.16.3.0/24 network.

Explanation: The second entry in the table indicates that there is one feasible successor (“1 successors”) for network 192.168.1.8/30. The last entry in the table shows that network 192.168.10.8/30 is directly connected, so it is not reachable through network 192.168.11.1. The third entry indicates that that the reported distances for network 192.168.1.0 are 28116 and 2170112, not 41024256. This same entry shows that neighbor 172.16.6.1 is a feasible successor for network 192.168.1.0. The first entry indicates that R1 has only one successor, not two to network 172.16.3.0/24.

2. Refer to the exhibit. After the configuration shown is applied on router R1, the exhibited status message is displayed. Router R1 is unable to form a neighbor relationship with R2 on the serial 0/1/0 interface. What is the most likely cause of this problem?

Chapter 4: Quiz - Troubleshooting EIGRP for IPv4 (Answers) CCNPv8 ENARSI 11

  • The passive-interface command should have been issued on serial 0/1/0.
  • The hello interval has been altered on serial 0/1/0 and is preventing a neighbor relationship from forming.
  • The network statement used for EIGRP 55 does not enable EIGRP on interface serial 0/1/0.
  • The IPv4 address configured on the neighbor that is connected to R1 serial 0/1/0 is incorrect.
  • The networks that are configured on serial 0/0/0 and serial 0/1/0 of router R1 are overlapping.

Explanation: According to the status message, serial 0/1/0 is receiving EIGRP packets coming from the IPv4 address 192.168.254.9. This IPv4 address is on a different subnet in contrast to the IP address configured on serial 0/1/0 of R1. The passive-interface command would have prevented any neighbor relationship from forming if the command was issued on serial 0/1/0. Changing the hello interval on one router and not another will not cause an EIGRP neighbor relationship to fail.

3. Refer to the exhibit. The routing table on R2 does not include all networks that are attached to R1. The network administrator verifies that the network statement is configured to include these two networks. What is a possible cause of the issue?

Chapter 4: Quiz - Troubleshooting EIGRP for IPv4 (Answers) CCNPv8 ENARSI 12

  • The AS number does not match between R1 and R2.
  • The network statements should include the wild card mask.
  • The no auto-summary command is missing in the R1 configuration.
  • The interfaces that are connected to these two networks are configured as passive interfaces.

Explanation: The fact that R2 has a route to 172.18.100.0 from R1 indicates that EIGRP is functioning, which excludes the issue of an AS number not matching. The issue is that both sides have a network within the Class B 172.16.0.0/16 network. Therefore, automatic network summarization must be disabled by the no auto-summary command. If this command is not used, the network statement with a wild card mask will not have effect. The passive interface, if configured, will prevent EIGRP updates from entering the two networks, but not prevent R1 from advertising them to R2.

4. Refer to the exhibit. Two routers have been configured to use EIGRP. Packets are not being forwarded between the two routers. What could be the problem?

Chapter 4: Quiz - Troubleshooting EIGRP for IPv4 (Answers) CCNPv8 ENARSI 13

  • EIGRP does not support VLSM.
  • The routers were not configured to monitor neighbor adjacency changes.
  • The default bandwidth was used on the routers.
  • An incorrect IP address was configured on a router interface.

Explanation: The interfaces that connect routers A and B are not addressed in the same subnet. For that reason packets will not be sent between the routers.

5. Refer to the exhibit. Router CiscoVille has been partially configured for EIGRP authentication. What is missing that would allow successful authentication between EIGRP neighbors?

Chapter 4: Quiz - Troubleshooting EIGRP for IPv4 (Answers) CCNPv8 ENARSI 14

  • The interfaces that will use EIGRP authentication must be specified.
  • The same key number must be used on any EIGRP neighbor routers.
  • The keychain for EIGRP authentication must be configured on the interfaces.
  • The CiscoVille router requires a second keychain to function correctly when using two interfaces for EIGRP authentication.

Explanation: The ip authentication key-chain eigrp 1 EIGRP_key command for EIGRP authentication has not been applied on each interface that participates in EIGRP authentication. EIGRP authentication steps include the creation of a keychain, a key ID, and a key string that is the equivalent of a password. EIGRP authentication is used on interfaces by selecting the interface to configure and then enabling MD5 authentication. Finally, EIGRP authentication is activated when the keychain to be used is issued on the interface.

6. Refer to the exhibit. How did the router obtain the last route that is shown?

Chapter 4: Quiz - Troubleshooting EIGRP for IPv4 (Answers) CCNPv8 ENARSI 15

  • The ip route command was used.
  • The ipv6 route command was used.
  • Another router in the same organization provided the default route by using a dynamic routing protocol.
  • The ip address interface configuration mode command was used in addition to the network routing protocol configuration mode command.

Explanation: A default route is presented in EIGRP with an asterisk (*) and the 0.0.0.0/0 entry. The route was learned through EIGRP and the Serial0/0/1 interface on the router.

7. A network administrator is troubleshooting the EIGRP routing between two routers, R1 and R2. The problem is found to be that only some, but not all networks attached to R1 are listed in the routing table of router R2. What should the administrator investigate on router R1 to determine the cause of the problem?

  • Does the AS number match the AS number on R2?
  • Does the hello interval setting match the hello interval on R2?
  • Do the network commands include all the networks to be advertised?
  • Is the interface connected to R2 configured as a passive interface?

Explanation: The fact that some networks appear in the routing table of R2 indicates that there is basic EIGRP communication between R1 and R2. This excludes the possibility of AS number mismatch and the interface between R1 and R2 being passive. Hello interval timers between EIGRP routers do not have to match. The administrator needs to make sure that the network commands cover all networks attached to R1 that should be advertised.

8. Refer to the exhibit. R3 has two possible paths to the 172.16.99.0 network. What is the missing value of this output?​

Chapter 4: Quiz - Troubleshooting EIGRP for IPv4 (Answers) CCNPv8 ENARSI 16

  • 2340608
  • 2816
  • 10512128
  • 2852608

Explanation: Feasible distance represents the lowest metric to reach the destination network and is the metric installed in the routing table. The feasible distance of the successor route for the 172.16.99.0 network is 2852608.

9. A network administrator wants to verify the default delay values for the interfaces on an EIGRP-enabled router. Which command will display these values?

  • show ip protocols
  • show running-config
  • show interfaces
  • show ip route

Explanation: The show interfaces command is used to show the delay, in microseconds, of a specified interface. This command will also provide the default delay value or an administratively configured value. The show running-config command will only display an administratively configured value. The commands show ip route and show ip protocols will not provide the delay value of each interface.

10. Refer to the exhibit. Routers R1 and R2 are directly connected via their serial interfaces and are both running the EIGRP routing protocol. R1 and R2 can ping the directly connected serial interface of their neighbor, but they cannot form an EIGRP neighbor adjacency.

What action should be taken to solve this problem?

Chapter 4: Quiz - Troubleshooting EIGRP for IPv4 (Answers) CCNPv8 ENARSI 17

  • Enable the serial interfaces of both routers.
  • Configure EIGRP to send periodic updates.
  • Configure the same hello interval between the routers.
  • Configure both routers with the same EIGRP process ID.

Explanation: In EIGRP configuration, the command that starts the EIGRP process is followed by a number that is the autonomous system (AS) number, router eigrp as-number. The as-number must be the same in all routers that are in the same EIGRP routing domain. In this case, R2 is configured with AS 80, and R1 is configured with AS 50.

11. While troubleshooting an EIGRP problem on a router, a network engineer needs to verify the IPv4 EIGRP implementation. To check the IP addressing, queue counts, and hold times for the adjacent routers, which command should be used?

  • show ip eigrp topology
  • show ip eigrp neighbors
  • show ip protocols
  • show ip eigrp interfaces

Explanation: Only the show ip eigrp neighbors command displays the IP addressing of the neighbor routers, the queue counts, and hold times.

12. Refer to the exhibit. Why did R1 and R2 not establish an adjacency?

Chapter 4: Quiz - Troubleshooting EIGRP for IPv4 (Answers) CCNPv8 ENARSI 18

  • The AS number does not match on R1 and R2.
  • The automatic summarization is enabled on R1 and R2.
  • The IPv4 address of Fa0/0 interface of R1 has a wrong IP address.
  • There is no network command for the network 192.168.1.0/24 on R1.

Explanation: To establish adjacency, both routers must be configured with the same AS number. The network 192.168.0.0 .0.0.255.255 command issued on R1 includes all networks from 192.168.0.0 to 192.168.255.255. Therefore, the network 192.168.1.0/24 is also included.

13. For troubleshooting missing EIGRP routes on a router, what three types of information can be collected using the show ip protocols command? (Choose three.)

  • any interfaces that are enabled for EIGRP authentication
  • any interfaces on the router that are configured as passive
  • the IP addresses that are configured on adjacent routers
  • any ACLs that are affecting the EIGRP routing process
  • networks that are unadvertised by the ElIGRP routing protocol
  • the local interface that is used to establish an adjacency with EIGRP neighbors

Explanation: The show ip protocols command verifies whether automatic summarization is being used on the local router, whether any interfaces on the local router are configured as passive interfaces, whether a network is not advertised to EIGRP neighbors, and whether any ACLs are applied to EIGRP.


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