set ntp time source in Windows Server 2003 Domain Controller

alter the registry:

HKLMSYSTEMCurrentControlSetServicesW32TimeParametersType
from NT5DS to NTP

HKLMSYSTEMCurrentControlSetServicesW32TimeConfigAnnounceFlags
from 10 to 5

HKLMSYSTEMCurrentControlSetServicesW32TimeParametersNtpServer
set the time server (add ,0x1 to the address to use DNS name: time.windows.com,0x1 )

net stop w32time
net start w32time
w32tm /resync /rediscover