NTP (Network Time Protocol) synchronizes the time for time servers and clients. You can use it to synchronize your routers, switches, and access points. Synchronization also makes logs more useful, by ensuring that the timestamps are reliable.
Unfortunately, a number of things can go wrong with NTP synchronization. If NTP isn’t working properly, there are several debug commands you can use to help troubleshoot the problem.
To initiate any debug commands, first make sure service timestamps are on:
service timestamps debug datetime localtime msec
You can then use debug commands such as the following:
debug ntp events
debug ntp errors
For further information, there are additional debug commands available, including:
debug ntp packet
debug ntp validity
debug ntp authentication
The first one (packet) shows you the NTP packets. The second (validity) displays failed tests. The third shows the authentication key ID.
Another thing you can try if NTP isn’t working is to set client times close to the proper time. If the time is too far off, NTP may not kick in.
For more information on common NTP problems and troubleshooting steps, see the following link:
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