300-440 Question 57
Select 2A network administrator is configuring OSPF between two routers, R1 and R2. Despite having matching OSPF configurations, the routers fail to establish a neighbor relationship. Upon investigation, the administrator finds an authentication mismatch. Which of the following actions will resolve the issue?
- A
Ensure both routers use the same authentication type (e.g., MD5 or plain-text).
- B
Verify the OSPF area ID matches on both routers.
- C
Configure the same authentication key on both routers.
- D
Set the OSPF router IDs to be identical on both routers.
- E
Ensure both routers are configured to use the same interface for OSPF authentication.
Show answer and explanation
Correct answers: A, C
Explanation
OSPF authentication ensures secure communication between routers. For a neighbor relationship to form, the authentication type and the key must match on both routers. If there is an authentication mismatch, focusing on these two factors will resolve the issue. Other parameters, such as area ID or router ID, are important for OSPF but unrelated to authentication mismatches.
- A. Correct.
Correct: OSPF requires both routers to use the same authentication type (e.g., MD5 or plain-text) to establish a neighbor relationship.
- B. Incorrect.
Incorrect: While OSPF area IDs must match for neighbor relationships, this is unrelated to resolving authentication mismatches.
- C. Correct.
Correct: Both routers must be configured with the same authentication key to successfully authenticate OSPF packets.
- D. Incorrect.
Incorrect: OSPF router IDs must be unique in the OSPF domain and do not affect authentication mismatches.
- E. Incorrect.
Incorrect: While the same interface can be used for authentication, it is not a requirement, and it does not resolve authentication mismatches.