http://blogs.technet.com/askds/archive/2007/11/01/configuring-your-pdce-with-alternate-time-sources.aspxBob Drake from Microsoft again. Often we see situations where the forest root domain PDCE is configured to acquire time from a specified authoritative NTP source but cannot due to issues outside of the local network (IE: DNS, Routing). Typically the firsten-USCommunityServer 2.1 SP1 (Build: 61025.2)