350-401 Question 397
Single answerYou are configuring OSPF between two routers, R1 and R2, in Area 0. Despite ensuring that both routers use the same OSPF area and network type, the neighbor relationship fails to establish. Upon further investigation, you discover that authentication is enabled on R2. Which configuration on R1 will resolve the issue?
- A
Enable OSPF authentication on R1 and configure a matching plaintext password.
- B
Enable OSPF authentication on R1 and configure a matching MD5 key.
- C
Disable OSPF authentication on R2 to match R1.
- D
Configure a different OSPF area on R1 to bypass authentication.
Show answer and explanation
Correct answer: B
Explanation
In OSPF, neighbor relationships require not only matching area and network parameters but also matching authentication types and credentials. If R2 is configured with MD5 authentication, R1 must also use MD5 authentication with the same key. Configuring R1 to match R2 resolves the issue while maintaining network security.
- A. Incorrect.
This is incorrect because OSPF authentication on R1 must match the type of authentication configured on R2. If R2 is configured with MD5 authentication, plaintext authentication will not work.
- B. Correct.
This is correct because OSPF authentication types and passwords must match on both routers. Configuring MD5 authentication on R1 with a matching key resolves the issue.
- C. Incorrect.
This is incorrect because disabling authentication on R2 is not a recommended solution. Authentication is often implemented for security, and bypassing it would compromise security policies.
- D. Incorrect.
This is incorrect because changing the OSPF area will not resolve the authentication mismatch. Both routers must remain in the same area for the neighbor relationship to form.