How to make a Windows XP machine an NTP server within a workgroup

Reason to do this

We have come across customer sites where a Windows Server is not present and yet the customer wants all workstations and devices to be time-synchronised to help when analysing log files and ensuring all workstations are running the same time reference.  The main Windows XP machine (hereinafter referred to as the source machine) is either synchronised to a separate NTP time source, or is corrected manually by checking/adjusting once a week.

How do I configure the source machine?

Whilst it is easy to make the source machine an NTP server for standard devices to synchronise with it, this does not qualify it as being authoritative to other Windows XP machines and an additional set of flags need to be suitably configured.

To simplify the configuration of your source machine, we have produced a registry file which you should download to the desktop of the source machine.

Here is the file:

This modifies the registry of the source machine to:

  • be an authoritative time source for Windows clients
  • to use NTP rather than an Active Directory domain source
  • to enable writing to the event log
  • to log NTP activity
  • to become an NTP server

Double-click on the registry file in order to allow regedit to update the machine's registry - you only do this to the source machine.  You can now delete the registry file as it is no longer needed.

It only remains to cycle the Windows time service so that the source machine actually takes account of the changes.  This will happen at the next reboot, or can be forced by dropping to a command prompt and typing:

net stop w32time&&net start w32time

That is all that is needed at the source machine.  You should now have a fully functioning NTP server which is also authoritative for Windows clients.  Routers, switches and other network devices that can use an NTP server, should all be pointed to this source machine's IP address.

How do I configure and test the client machines?

First, you need to configure the client machine to point to the source machine and synchronise from it.  If the source machine address is, for example, 192.168.128.1, then at the client machine you should drop to a command prompt and type:

net time /setsntp:192.168.128.1&&net stop w32time&&net start w32time&&w32tm /resync /rediscover

These four sequential commands: configure NTP to point to the source machine, cycle the Windows time service, rediscover network resources and, finally, resynchronise its clock as soon as possible.

Next, you can confirm that the client machine is working by reviewing its System event log with the Windows Event Viewer.  There should be a W32Time event, with an Event ID of 37, showing that, 'this computer is currently receiving valid time data from 192.168.128.1'.  Naturally, the actual address will be whatever you are really using on your own network.

Finally, repeat this process to each client computer on your workgroup so that they will all stay in synchronism with the source machine.

On a regular basis, ensure that the source machine is kept up-to-date with the actual time by manually updating its clock as it drifts away from the actual time.

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