Daylight savings time changes will cause disruptions this year

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Article update here.

In the United States, the rules on when Daylight Savings Time goes into effect have changed. For decades, DST went into effect on the first Sunday in April; starting this year it goes into effect the second Sunday in March, or March 11.

IT systems and applications that don’t know about the change will sail through March 11 without making the required time clock change, potentially throwing applications that rely upon the correct time into potential chaos. Those same systems will cause headaches again on April 1, when they do change and are not supposed to.

The same thing will happen again in late October of 2007. DST ends a week later, on the fist Sunday in November instead of the last Sunday in October. But hopefully any systems that malfunctioned in March will be fixed by October.

The sky is not falling. This isn’t Y2K, where the fear of wider and deeper system malfunctions caused a global mobilization of fixes, patches, and migrations to Y2k-compliant systems and software.

Many IT professionals misunderstand this problem. NTP will not fix this. NTP (Network Time Protocol, the global network of ultra-accurate time synchronization) is DST-agnostic: NTP broadcasts time in GMT and does not transmit DST information. It is up to every computer (and software program that calculates DST) to correctly calculate the DST offset. Do not get caught in the “NTP will fix this for us” trap.

There are a lot of good articles on this. Here are a few:

http://www.networkworld.com/news/2007/012507-daylight-saving.html

http://computerworld.com/action/article.do?command=viewArticleBasic&articleId=9009959&intsrc=hm_list

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One thought on “Daylight savings time changes will cause disruptions this year

  1. Pingback: NTP will NOT fix the DST issue « Peter H Gregory, CISA, CISSP

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