CCNA 200-125 Exam: EIGRP GRE Troubleshooting Sim With Answers

Refer to the topology below. Your company asks you to identify the issues in Phase 1 EIGRP implementation. You have console access on R1, R2, R3 Branch1 and Branch2 routers. Only use show commands to troubleshoot the issues.

You are implementing EIGRP between the main office and branch offices. In Phase 1, you must implement and verify EIGRP configurations as mentioned in the topology. In Phase 2 your colleague is expected to do NAT and ISP configurations.

Identify the issues that you are encountering during Phase 1 EIGRP implementation.
– Router R1 connects the main office to the Internet and routers R2 and R3 are internal routers.
– Routers Branch 1 and Branch2 connect to router R2 in the main office.
– Users from the Branch 1 LAN network 10.20.40.0/24 are expected to perform testing of the application that is hosted on the servers in Server farm1. before servers are available for production.
– The GRE tunnel is configured between R3 and Branch1, and traffic between server farm1 and Branch 1 LAN network 10.20.40 0/24 is routed through the GRE tunnel using static routes.
– The line between Branch 1 and Branch is used as a secondary path in the event of failure of the primary path to main office

You have console access on R1, R2, R3 Branch 1, and Branch2 devices use only show commands to troubleshoot the issues

1. Examine the R1 routing table. None of the internal routes other than locally connected appear in the routing table. Which cause of the issue is true?
   • A. EIGRP neighbor relationship was not formed due to AS mismatch between routers R1 and R2
   • B. EIGRP neighbor relationship was not formed due to K values mismatch between routers R1 and R2
   • C. EIGRP packets were blocked by the inbound ACL on R1
   • D. IP address was misconfigured between the R1 and R2 interface*
   Show (Hide) Explanation/Reference

   R1 routing table does not have any EIGRP learned routes so R1 or the link between R1 & R2 is the most likely problem. We should check if the IP addresses on R1 and R2 are correct or not with the “show ip interface brief” command.

   

   Note: You should check the IP address of R2 E0/0 interface (the interface connected to R1) as well.
2. The traffic from Branch2 to the main office is using the secondary path instead of the primary path connected to R2. Which cause of the issue is true?
   • A. The network 192.168.11.0/30 was not advertised into EIGRP on Branch2
   • B. The IP address was misconfigured between the Branch2 and R2 interfaces
   • C. EIGRP packets were blocked by the inbound ACL on Branch2*
   • D. The primary path has more link delay configured than secondary path which causes EIGRP to choose the secondary path
   Show (Hide) Explanation/Reference

   The “main office” here refers to R2 (and other routers behind it). Check Branch2 with the “show ip route” command:

   

   We can see Branch2 only uses 192.168.12.1 (Branch 1 – the secondary path) to reach R2 and the subnets behind. Branch2 does not use the primary path (directly connected to R2) so there must be a problem with the connection between R2 and Branch2. Check Branch2 router with the “show running-config” command and we can see an access-list is blocking EIGRP packets advertised to Branch2.

   
3. The GRE tunnel between R3 and Branch1 is down. Which cause of the issue is true?
   • A. The tunnel source loopback0 interface is not advertised into EIGRP in Branch1
   • B. The tunnel source loopback0 interface is not advertised into EIGRP in R3
   • C. The EIGRP neighbor relationship was not formed due to EIGRP packets blocked by inbound ACL on R3*
   • D. The EIGRP neighbor relationship was not formed due to the IP address being misconfigured between the R2 and R3 interfaces.
   Show (Hide) Explanation/Reference

   This issue is same as Question 2 but this time it is R3 which causes the issue. We can check R3 with the “show running-config” command.

   
4. You are verifying the EIGRP configurations in the topology. Which statement is true?
   • A. Branch2 LAN network 172.16.11.0/24 is not advertised into the EIGRP network
   • B. Branch2 LAN network 172.16.10.0/24 is not advertised into the EIGRP network
   • C. R3 server farm2 network 10.20.30.0/24 is not advertised into the EIGRP network
   • D. Branch1 LAN network 172.16.12.0/24 is not advertised into the EIGRP network*
   Show (Hide) Explanation/Reference

   In this question we should check the local routers to see if these subnets have been advertised or not as there are many issues in the path which prevent these subnets from being shown in the routing tables.

   When checking Branch1 router, we notice “network 172.16.0.0” is missing under EIGRP 200 so answer D is correct.