350-401 Question 191
Single answerA network engineer is troubleshooting time synchronization issues in a network using NTP. The following configuration is applied on a Cisco router:
ntp server 192.168.1.10
ntp authenticate
ntp trusted-key 1
ntp authentication-key 1 md5 cisco123
Despite this configuration, the router fails to synchronize with the NTP server at 192.168.1.10. What could be the possible reason?
- A
The NTP server at 192.168.1.10 is not reachable from the router.
- B
The authentication key ID used in the configuration does not match with the key ID configured on the NTP server.
- C
The NTP server does not support authentication, which is causing the synchronization to fail.
- D
The 'ntp authenticate' command is not required when only one NTP server is configured on the router.
Show answer and explanation
Correct answer: B
Explanation
The provided configuration enables NTP authentication with a specific key ID and value. For the router to successfully synchronize with the NTP server, the key ID and key value must match between the router and the server. If the key ID or key value differs, authentication fails, and synchronization cannot occur. This scenario highlights the importance of correctly matching NTP authentication parameters when using the 'ntp authenticate' command.
- A. Incorrect.
While server reachability is critical, this is not specific to the issue described, as the problem is related to authentication configuration.
- B. Correct.
If the authentication key ID configured on the router does not match the key ID on the NTP server, authentication will fail, causing the synchronization issue.
- C. Incorrect.
If the NTP server does not support authentication, the router would still synchronize as long as authentication is not enforced. The scenario does not indicate that authentication is enforced.
- D. Incorrect.
The 'ntp authenticate' command is necessary when using authenticated NTP configurations, regardless of the number of servers.