The Network Time Protocol service is responsible for time sync in all the domain controllers. Among all DCs, the PDC FSMO role holder plays a role of central time server. Have you ever gone through following error:
"The Network Time Protocol service on ServerName started and then stopped. Some services stop automatically if they are not in use by other services or programs."
No matter how many times you will start that service, it will automatically stop immediately.
If you go and see the NTP server log in "C:\Program Files\NTP\ETC\ntp.log" file, you will see multiple errors like:
21 Sep 00:36:01 ntpd: unable to bind to wildcard address :: - another process may be running - EXITING
21 Sep 00:36:01 ntpd: ntservice: The Network Time Protocol Service is stopping.
The error comes because there are multiple instances of a service is running on same port. All network protocol related services use port No: 123 and in Windows server, both "Network Time Protocol" service and "Windows Time" service run on same port 123 by default. You can customize different ports for both services later.
So here comes the solution. Just stop "Windows Time" service in the server and then start "Network Time Protocol" service. It will start properly. Once you have started "Network Time Protocol (NTP)" service, you can again start "Windows Time (W32Time)" service successfully.