We have 2 3560's that might have a problem as neither switch will no longer display the 'Last configuration change' or the 'NVRAM config last updated' lines when running 'sh config'. So far, I can ping devices located on each switch.
Also when doing a 'sh clock' both switches will display '*HH:MM:SS.mmm PST Tue Mar 2 1993'.
Both clocks can successfully ping the ntp server.
Any ideas for troubleshooting?
The reason that the Last configuration change does not show up is that the switch no longer knows the authoritative time. If the switch knows authoritative time it will include the Last configuration change and if it does not know time then it does not.
So the issue is why do the switches no longer learn NTP. Do I understand from your post that they are configured for NTP? Did NTP work at one point and now it does not work?
Perhaps you can post the NTP configuration. I can think of several things that might cause this but seeing the configuration would be a good place to start.