200-301 Question 362
Single answerA network administrator is tasked with configuring NTP in a small network. RouterA needs to act as an NTP server, and RouterB should synchronize its time with RouterA. After configuring the following commands on RouterA:
RouterA(config)# ntp master 2
The administrator then configures the following commands on RouterB:
RouterB(config)# ntp server 10.1.1.1
RouterB(config)# ntp authenticate
RouterB(config)# ntp authentication-key 1 md5 cisco123
RouterB(config)# ntp trusted-key 1
However, RouterB is not synchronizing its time with RouterA. What is most likely causing the issue?
- A
The NTP master command on RouterA is missing an authentication configuration.
- B
RouterB is not configured to use the correct authentication key ID.
- C
RouterA does not support the NTP master command with authentication enabled.
- D
The IP address of RouterA is incorrectly configured on RouterB.
- E
NTP authentication is not required in this scenario and should be disabled on RouterB.
Show answer and explanation
Correct answer: B
Explanation
The issue lies in the mismatch of NTP authentication configurations between RouterA and RouterB. RouterA is configured as an NTP server but does not have authentication enabled, while RouterB is configured to use authentication. For the synchronization to occur, either authentication must be enabled on RouterA with the correct key ID and key value, or authentication must be disabled on RouterB.
- A. Incorrect.
The NTP master command does not require explicit authentication configuration. RouterA is already set up to act as an NTP server.
- B. Correct.
RouterB explicitly configured NTP authentication, but the authentication key ID (key 1) must match the key ID on RouterA. Since RouterA does not have authentication configured, the mismatch prevents synchronization.
- C. Incorrect.
The NTP master command supports authentication if configured, but in this scenario, RouterA is missing the relevant authentication configuration.
- D. Incorrect.
The IP address of RouterA (10.1.1.1) is correctly configured on RouterB as the NTP server. This is not the issue.
- E. Incorrect.
NTP authentication is optional, but since RouterB is explicitly configured to use it, disabling it would not resolve the configuration mismatch.