Configure NTP Time Service on Windows Server DC
To configure an authoritative NTP Time Server (on Windows Server Domain Controller) to synchronize with an external NTP time source, edit following Windows registry entries:
Change the time server type to NTP
Set to NTP
NTP stands for Network Time Protocol
Set AnnounceFlags to 5
Set to 5
Announce flag values:
0 Timeserv_Announce_No, Reliable_Timeserv_Announce_No. The domain controller does not advertise time service.
1 Timeserv_Announce_Yes. The domain controller always advertises time service.
2 Timeserv_Announce_Auto. The domain controller automatically determines whether it should advertise time service.
4 Reliable_Timeserv_Announce_Yes. The domain controller will always advertise reliable time service.
8 Reliable_Timeserv_Announce_Auto. The domain controller automatically determines whether it should advertise reliable time service.
Flag 5 (1+4) means "The domain controller always advertises time service" and "The domain controller will always advertise reliable time service".