On a customer site we noticed that the time was 20 minutes out on all servers. The PDC emulator was configured to sync with time.windows.com however when running w32tm /resync it was failing with the following error:

After checking the outbound NTP firewall rule for time.windows.com, we noticed that the IP address had been specified rather than the FQDN.

We ran an NSLOOKUP to find the IP address had changed to 207.46.232.182