350-401 Question 387
Single answerA network engineer is troubleshooting an EIGRP issue between two routers, R1 and R2, which are directly connected. Both routers are configured in named mode under the same EIGRP instance. However, the EIGRP adjacency is not forming. Upon inspection, the following observations are made:
- R1 is operating in the global VRF, while R2 is configured under a VRF named 'VRF1'.
- The EIGRP instance name and AS number are correctly configured on both routers.
- The IP addressing on the directly connected interfaces is correct, and both interfaces are up.
What is the most likely cause of the issue?
- A
The EIGRP timers are mismatched between R1 and R2.
- B
The EIGRP authentication configuration is missing on both routers.
- C
R1 and R2 are operating in different VRFs, causing the adjacency failure.
- D
EIGRP named mode does not support adjacency formation between global and VRF interfaces.
Show answer and explanation
Correct answer: C
Explanation
For an EIGRP adjacency to form, both routers must operate in the same VRF context or in the global routing table. In this scenario, R1 is in the global VRF, and R2 is in 'VRF1', which prevents them from forming an adjacency. To resolve the issue, ensure both routers are configured under the same VRF context or move the EIGRP instance to the global routing table on R2.
- A. Incorrect.
EIGRP timers mismatched would not prevent the adjacency from forming; it would typically lead to suboptimal routing or delays. This is not the root cause in this scenario.
- B. Incorrect.
While authentication mismatches can prevent adjacency formation, the scenario does not mention any authentication configuration. Additionally, the problem is related to VRF configuration differences.
- C. Correct.
EIGRP adjacencies cannot form between routers operating in different VRFs, even if other configurations such as instance name and AS number are correct. This is the most likely cause of the issue.
- D. Incorrect.
EIGRP named mode supports both global and VRF configurations. The problem is not related to named mode limitations but rather the VRF mismatch.