KB2007.103
FAQ: How do changes in Daylight Saving Time or time zones affect Domain Time?

This article applies to Domain Time II.

Last updated: 11/10/2008

Question


How do changes in Daylight Saving Time or time zones affect Domain Time?

Answer


Domain Time both obtains and provides time using Universal Coordinated Time (UTC). It is unaffected by time zone settings on the local machine or by changes in Daylight Saving Time. No changes or updates to Domain Time are required for changes in time zones or Daylight Saving Time.

Background
Operating systems such as Windows, UNIX, Linux, and others use UTC time for their internal system clock. The OS then calculates what time to display to the user or applications by applying local time zone settings to the UTC time. The time zone settings used are set on the individual machine (such as in Window's Date and Time Control Panel applet).

Changes in Daylight Saving Time are specific to particular time zones and local laws. These laws change periodically, so you will need to contact the operating system vendor to obtain time zone updates for your locality.

Suggested reading:
See Microsoft KB914387 for more information on how Windows handles Daylight Saving Time. You may want to use the TZEDIT utility referenced in the KB to examine your own machine's start and end dates if it appears your machine suddenly is off by exactly one hour near the beginning or end of Daylight Saving Time.