How to synchronize to a NTP server on Windows XP?

Solution 1:

• Make sure the Windows Time (w32time) service is running. (Either through services.msc, or sc query w32time and sc start w32time.)
• Try running w32tm /register as an administrator.
• Try manual configuration: w32tm /config /manualpeerlist:pool.ntp.org /update
• ...and manual resync: w32tm /resync
• Also open eventvwr.msc and check the Application and System logs for errors.

Solution 2:

Quick note for anyone who comes across this solution in the future -- if the command above doesn't work, add /syncfromflags:manual in there as well like this:

w32tm /config /manualpeerlist:pool.ntp.org /syncfromflags:manual /update