An administrator is testing new configuration on a network device. The network device had a previously established association with the NTP server but is no longer processing time updates. What is…

A server changing its time source to stratum 1 (a highly accurate source) would generally improve time synchronization, not cause it to stop.

This choice describes the symptom (wrong password) if authentication is misconfigured, but the root cause is that authentication itself was enabled on the device, requiring a password to be sent.

If NTP authentication has been configured on the network device, but not correctly matched on the NTP server or if the keys are mismatched, the device will fail to authenticate with the server and thus stop processing time updates, even if a previous association existed without authentication.

If NTP authentication was only configured on the NTP server, a client device without authentication configured would simply fail to establish an authenticated connection from the start, not lose an *established* unauthenticated association unless the server was configured to *require* authentication subsequently, which is a less direct cause than the client device's new configuration.