Time sync with external NTP on windows server 2008 R2 DC

1. Locate PDC - C:\>netdom /query fsmo
2. Log in to PDC Server and open the command prompt.
3. Stop the W32Time service: C:\>net stop w32time
4. Configure the external time sources, type: C:\> w32tm /config /syncfromflags:manual /manualpeerlist:”0.pool.ntp.org, 1.pool.ntp.org, 2.pool.ntp.org”
5. Make your PDC a reliable time source for the clients. Type: C:\>w32tm /config /reliable:yes
6. Start the w32time service: C:\>net start w32time
7. The windows time service should begin synchronizing the time. You can check the external NTP servers in the time configuration by typing: C:\>w32tm /query /configuration
8. Check the Event Viewer for any errors.

NOTE: Make sure your firewall allows NTP out before you do this or your DC will not be able to contact outside NTP servers.