Where do Windows 2000 and Windows NT store time zone information?

A. From the Control Panel Date/Time applet, select the Time Zone tab to set the local country and its associated time difference. You can select the same tab to enable daylight saving.

Changing these settings updates the registry values under the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation key. I’ve listed the most useful time-zone values below.

ActiveTimeBias	This value is the current time difference from Greenwich Mean Time (GMT) in minutes and is the difference for GMT. For example, if you’re 1 hour ahead, GMT is 1 hour behind. The value would be ffffffc4, which is hexadecimal for -60.
Bias	This value is the normal time difference from GMT, excluding daylight saving in minutes. The value is the difference for GMT, so if you’re 3 hours ahead (e.g., if you live in Moscow), the Bias would be ffffff4c, which is hex for 180. If you’re 2 hours behind GMT (e.g., if you're on a boat in the mid-Atlantic Ocean), GMT is 2 hours ahead, so the value is 120.
DaylightBias	This value is the time difference used for daylight saving for GMT. If you're 1 hour ahead, the value is ffffffc4, which is hex for -60. Notice that the ActiveTimeBias is the sum of Bias and DaylightBias in daylight saving months, which is the same as Bias for standard months.
DaylightName	The OS uses this name during daylight saving months.
StandardName	The OS uses this name during non-daylight saving months.
DaylightStart	This value tells the computer when to start daylight mode.
StandardStart	This value tells the computer when to start standard mode.
DisableAutoDaylightTimeSet	This value exists only if you clear the checkbox for the option Automatically adjust clock for daylight saving and if you set the value to 1.

Using the Microsoft Windows 2000 Resource Kit or the Microsoft Windows NT Resource Kit reg.exe utility, you can use the following command to query these values from the command line:

C:\>reg query hklm\system\currentcontrolset\control\timezoneinformation\bias REG_DWORD bias 0 C:\>reg query hklm\system\currentcontrolset\control\timezoneinformation\daylightname REG_SZ daylightname GMT Daylight Time

End of Article

Very nice, I needed to know those defined values. But I have one problem:

I export the string and edit the .reg file, cause I want to enable automatic daylight time setting. I do this by changing the value from "00000001" to "00000000", save it and add it by double clicking. Trouble is, it doesn't put it in effect. I know this, cause when I adjust date and time, the DST is checked - and when I click "OK" it adds an hour! And it only happens when I have the timezone tab active!

Now, as far as I have understood, the checkmark does not change system time, it adds an hour to it in Windows 2000. This means the time shown in my system tray should be actual time +01:00 when DST is put active. How do I get my system to acknowledge this, without entering "Date & Time", changing tab and then clicking "OK"?

A lot of work, just to change a setting. Well, not if you could automate the process for 100 clients during logon. My users would not be able to understand the process of changing this setting, so I need this solution badly.

Christen Stephansen April 07, 2003

Yes Christen I have the same problem, want to enforce DST on our network but need to click OK before the change will take affect. Very annoying.

Nick T November 17, 2003

I need a small help from you.
I would like to change the time zone using a batch file.
eg:timzone "Indian Standard Time"
where, timezone is the exe and it accepts argument for changing the time zone to another one.
Currently if Iam in PST, it should change to IST.
Would appreciate help from you!

Thanks,
Karthik

Karthik March 25, 2004

We have a W2K server running Lotus Domino. It periodically and spontaneously loses all time zone information and the O/S switches from our time to GMT, some six hours in advance. If I open the W2K date-time controls, not only is it not set to our time zone (Central US), but there are no zones to chooose in the drop-down. All blank.

This wreaks havoc with our Domino server.

Has anyone else encountered anything similar? Any suggestions?

Anonymous User November 20, 2004 (Article Rating:

)

Hi,
This article is very informative but i have a peculiar problem. I want to change Time Zone of the users at Login Time as same PC's are being shared by many users and different users require different Time Zones. If I run a script to modify the HK LM Time Zone Key then i need Administrative Rights which the user would not have.
I would really appreciate any help on this issue.
Thanks,
Jaspreet

Jaspreet Jolly May 29, 2005 (Article Rating:

)

I learned something..But I want to change timezone of users at login time as same PCs are being shared by many users..Different team of users required different time zone.

venware October 19, 2006 (Article Rating:

)

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