The W32Time service

Every server should always have an accurate system clock. This is especially important if the server uses systems like Shibboleth because they place time restrictions on the data that is being transmitted to enhance security. Windows provides a built-in NTP client from version 2000. It allows you to synchronize the time of this server to a special NTP server somewhere in the internet by running the NTP client on this server. For Windows Server 2003 and Windows XP the NTP client is enabled by default (in that case you do not have to use this small guide).

The W32Time Service is a fully compliant implementation of the Simple Network Time Protocol (SNTP) as detailed in IETF RFC 1769. SNTP uses UDP port 123 by default. If you want to synchronize your time server with an SNTP server on the Internet, make sure that port is available.

Console commands

c:\net time /setsntp:ntp.belnet.be
c:\net start W32Time

Running as a service

You can also set the start option of the Windows Time Synchronization Service (W32Time) to Automatic, so the service will start when Windows starts.

Windows Registry settings

Set the correct value for the following Registry entries. (http://support.microsoft.com/kb/q223184/)
The registry values are located in the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters