Impact of the Congressional change in 2007 for Daylight Savings Time

This article contains information that may answer questions from customers regarding upcoming patches / tools needed to correctly handle the changes to Daylight Saving Time (DST) in the US and elsewhere across the world resulting from the Energy Policy Act of 2005.


Starting in the spring of 2007, daylight saving time (DST) start and end dates for the United States will transition to comply with the Energy Policy Act of 2005. DST dates in the United States will start three weeks earlier (2:00 A.M. on the second Sunday in March) and will end one week later (2:00 A.M. on the first Sunday in November). This will impact not just our US customers, but international customers and partners who transact business with companies in the US.


Impacted Dates for 2007 (please note: dates may change in future years):


Previous DST Start       New DST Start 

1st Sunday of April       2nd Sunday of March

April 1, 2007                March 11, 2007


Previous DST End               New DST End

Last Sunday of October      1st Sunday of November

October 28, 2007                November 4, 2007


The change in DST will have an impact on many automated and technology reliant products. Individual consumers, small to medium size businesses and large enterprises may be impacted by the new change in time. In many cases, making the necessary changes to accommodate the new DST legislation will be a relatively minor task. Users may need to manually adjust the time on their devices when the change occurs.


Microsoft is producing updates for Microsoft products affected by the new United States daylight saving time transition dates. These updates will be released through a combination of channels including Microsoft Customer Support Services (CSS), hotfixes incorporated in Knowledge Base articles, Windows Update, Microsoft Update, Windows Server Update Services (WSUS), and the Microsoft Download Center.


2 important points:


- This is NOT a fix and it is not something that Microsoft did wrong in the products. This is a change to country laws that Microsoft is taking a proactive position in addressing. It affects everyone in this industry and many others. It’s important that we not act like or communicate that we “broke something” as the wording “fix” implies.


- Public information is constantly being updated and you should keep abreast of the changes. We’ll try to keep everyone updated. We expect customer segment focused content to be available in the coming weeks.


A Windows patch that updates the time zone definitions is currently available for download. The update for pre Vista systems is obtained via KB 928388  <>. These updated time zone definitions will also be included with Windows Vista.



Impact to SMS:


None at this time since it primarily relies on the OS for getting time information. The expectation is that this will be the same as any other Daylight Saving Time change. For example, site servers that are not using UTC/GMT for software distribution may see advertisements starting an hour earlier or later (local client time) at the time of the changeover. If any significant issues are discovered they will be communicated appropriately.




As of 1/31/2007 the DST patch will not deployable via ITMU. It is of course deployable using normal software distribution.



IMPORTANT: On February 13 (next Patch Tuesday) there will be an update to the DST OS patch, and it will be marked as a Critical Update.

The plan at this time – subject to change pending final testing – is to release the patch as an Update Rollup at the same time.


As a result, the patch Will be available in the WSUSSCAN/WSUSCN2 cab file, and therefore in ITMU.



ITMU works only with the contents of the / file.

This .CAB file comes from the Microsoft Update team and only contains data on updates matching one of these 3 categories:

- Security

- Update Rollup

- Service Pack


The DST patch does not fall into any of the above categories, and as a result is not in the .CAB file that ITMU will consume. The remaining 2 categories are Critical Update and Update.


This design will not change for SMS 2003, but it has been changed for v4.

SMSv4 (SCCM) and its integration with WSUS3 would offer the DST updates as critical updates when they are flagged as such.



Manual Changes (Windows 2000)


Hardware Inventory Implications:


The vast majority of Windows 2000 customers do not have the necessary Extended Hotfix Support Agreement (EHSA) required to get a patch from Microsoft that they can deploy. As a result they will be pushing out manual changes. KB 914387 <> covers the details of this.


Customers may be pushing out .REG files with SMS or placing them on common file shares and simply advertising the command line (no package source files). For reporting it’s likely they will extended the SMS_DEF.MOF to collect the TimeZone registry key. As a result you should be prepared for potential hardware inventory related issues, and make sure you are familiar extending the .MOF file to include a new registry key. See


More details for Win2K deployments will almost certainly appear soon on community sites such as myitforum and intelliadmin. Be aware of their contents, but also know that any solutions they offer likely are not be supported.



Impact to Outlook


Microsoft Office Outlook 2007, the newest version of Outlook, can automatically update a person's calendar to conform to the new daylight saving time rules. For other releases of Outlook, a program will be released in late January 2007 at the Microsoft Download Center that can update calendar items in Microsoft Office Outlook to accommodate the changes in DST during the extended DST period. This program is called the Time Zone Data Update Tool for Microsoft Office Outlook.


For more detailed information of this issue, please refer to the following article.


Outlook: Prepare calendar items for daylight saving time changes in 2007



Impact to Directory Service:


The customers may have concerns regarding the hotfix 924840 in the domain-based environment. A common question is whether the Daylight savings Time Change patch will affect the active directory? Basically, the  Directory services rely on the Windows Time Service (W32Time), which is based on the Simple Network Time Protocol (SNTP) as specified in RFC RFC 1769 (now superseded by RFC 2030). SNTP is designed to ensure loose synchronization only, which in the W32Time implementation means the clocks of all Windows 2000/XP/2003 machines in a forest will agree within 20 seconds of one another (or 2 seconds difference within a particular site). W32Time expresses clock times in Coordinated Universal Time (UTC), an atomic time scale previously known as Greenwich Mean Time (GMT).


The daylight savings 2007 patch only updates the time zone information in the registry. Active Directory does not rely upon this time zone registry for its functioning. In that, the hotfix 924840 has no impact to the Domain Controllers.

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