Change Default Sync Value
By default, Windows checks the time against the time server once a week. If you want to use some other interval, go to
and set the decimal value of the SpecialPolInterval key to some other value in seconds.
Adding Multiple Time Servers at Once
One easy way to add a lot of time servers to the Registry at once is to create a REG file containing them in Notepad. For example, you could create the following text file in Notepad and save it as timesrvr.reg (or whatever name you want, as long as it has a .reg extension)
Windows Registry Editor Version 5.00
You can keep going ad infinitum with the list, giving each time server you want to add a consecutive number. Then save your work and close Notepad. Locate the file in Windows Explorer, right-click it and click on merge.
Open Firewall Port
This does require access to the internet using UDP port 123
Restart the Windows Time Service after any changes.
Some steps to creating and running the files. Windows 2003 server, vista, windows 7 have a GUI to enabled syncing the computers clock with an external time source. XP does not.