Windows Time

There are two ways time is synced on windows machines NTP and NT5DS when a machine is joined to a domain the default type is NT5DS

Windows has a default ntp server set to time.windows.com but this will not be used by machines on a domain unless they are changed to use NTP instead of NT5DS.

This setting is stored HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\Type

    If you define a NTP server ( net time /setsntp:server.blah.corp) this setting will automatically be change to NTP

    If you remove the NTP server ( net time /setsntp ) this setting will automatically be change to NT5DS

By default when the w32time server starts on a machine it will poll every 45 minutes.

Articles

http://www.windowsnetworking.com/articles_tutorials/Configuring-Windows-Time-Service.html

http://blogs.msdn.com/w32time/default.aspx

http://technet.microsoft.com/en-us/library/cc779145%28WS.10%29.aspx