We just had a summer daylight change in US. and pc's on my network are behaving strange, some of them change time and some didn't.

My network: 2 locations both in Midwest, same time zone. Location 1: 120 pcs (windows xp & windows 200) , with 1 Active Direcotry Domain Controller on Windows 2003 Standard. A couple of windows 2000 servers (they up to date) the rest of the servers are Xen or Debian machines (all up to date) , Second location connected through OpenVPN link all pc's are running fine - but they are all connecting to our AD domain controller. Locaiton 2: 10 pcs, and a shared LAN NAS. Both of the routers/firewalls in both locations are pFsense boxes with ntp service running - but it's up to date.

Tried all the usual suspects:

  • I have all the latest updates installed
  • restarted them
  • domain controller is running fine
  • most computers are running fine
  • I have only one domain controller on my network
  • also my firewall serves as ntp server (pfsense) but it's up to date.
  • all of the linux machines are fine since they are querying firewall / router for the time.

about 1/3 of my pcs are 1 hour behind. If I change them manually they just change back ( the way domain pc's are supposed to).

I've tried everything but I can't think of anything else to try.


Time synchronization has nothing to do with time zones. Windows time synchronization and internal time is always UTC.

Check the following registry key on the clients that aren't updating to ensure they have the correct registry values. You can compare it to a computer that has the correct time zone.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\

  • Greg - right on the money. Regestry is wrong on those machines. What I don't understand is how that happened thou? And on so many machines? – konung Mar 16 '10 at 23:43
  • Sounds like the Microsoft time zone patch did not take, or had issues. If you're interested, you can create a GPO of that registry key (from your highest Windows version that is fully patched) and apply it to your Windows computers. As far as I can tell, that key has the same format on Windows 2000 - 2008, except 2008 has more time zones. This would actually be useful for your Windows 2000 machines, as they are end-of-life in a few months and there will not be any further time zone updates for them. – Greg Askew Mar 17 '10 at 0:29

Make sure that your win2k boxes really really have the fix on them if I'm remembering correctly the hotfix was only available for extended support customers and everyone else had to do it manually with these instructions

  • Zypher is right, several years ago, the US goverment changed the dates that Daylight Savings Time starts and ends. O/S's had those dates coded in, so they would change in April instead of March(and November instead of October). My recollection is that Win2K did not get this through the Service Pack nor Hot Fix, you had to download a program from the Resource Kit that let you edit the dates for your time zone. I think the program was called tzedit. – BillN Mar 16 '10 at 23:02
  • Sorry guys if I wasn't clear enough - my windows 2000 servers are NOT the problem. It's my client Windows XP machines that are not up to date and they have that update installed, that are the problem. Updates are set on automatic updates every sat. – konung Mar 16 '10 at 23:32

The command 'w32tm' is very useful for figuring this kind of thing out. It's the Windows time management tool.

w32tm /monitor

Run that on an affected machine and it'll tell you what it sees for time-sources. If it shows that the DCs its pulling time from have a minimal offset, and yet the station is still an hour behind, chances are real good that the local timezone files haven't been updated with the DST updates. If it shows one of your DCs as way out of sync with the others, that's where you want to focus your effort.

  • as expected - pointing to correct PDC - Active directory server. 0ms dedail, ntp + 0.0000000s offset – konung Mar 16 '10 at 23:34

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