I've had ongoing problems trying to get a Windows 2003 DC to get time from any NTP server on the web. I've tried following docs on the microsoft site to sync with an NTP server, but cannot get it working.
I find this message in the event viewer
Event Type: Error
Event Source: W32Time
Event Category: None
Event ID: 29
Time: 8:59:58 AM
The time provider NtpClient is configured to acquire time from one or more time sources, however none of the sources are currently accessible. No attempt to contact a source will be made for 120 minutes. NtpClient has no source of accurate time.