300-440 Question 204
Select 4A network administrator has configured AAA on a Cisco router to use a TACACS+ server for authentication. However, users are unable to log in to the router using their TACACS+ credentials, and the fallback to the local database is not working. Which of the following steps should the administrator take to troubleshoot the issue?
- A
Verify that the TACACS+ server is reachable from the router using ping or traceroute.
- B
Ensure the correct AAA login method list is applied to the lines used for user login.
- C
Check the shared secret key configured on the router matches the one on the TACACS+ server.
- D
Reconfigure the local username and password to bypass TACACS+ authentication.
- E
Review the TACACS+ server logs for authentication request details and potential errors.
Show answer and explanation
Correct answers: A, B, C, E
Explanation
Troubleshooting TACACS+ authentication involves verifying that the server is reachable, ensuring the correct AAA method list is applied, and confirming the shared secret key matches between the router and the server. Additionally, reviewing TACACS+ server logs can provide insights into why authentication requests are failing. Reconfiguring the local username and password does not address the core AAA configuration issues.
- A. Correct.
If the TACACS+ server cannot be reached, authentication requests will fail. Verifying connectivity using ping or traceroute is a critical step.
- B. Correct.
The AAA method list determines how users are authenticated. If the wrong method list is applied, the router might not even use TACACS+ or fallback to the local database.
- C. Correct.
A mismatched shared secret key between the router and the TACACS+ server will prevent successful authentication.
- D. Incorrect.
Reconfiguring the local username and password does not resolve the issue with AAA or TACACS+ and is not a recommended troubleshooting step.
- E. Correct.
TACACS+ server logs provide valuable information about the authentication process and can help identify configuration errors or request failures.