[ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Thu Mar 15 07:07:43 UTC 2012

unruh wrote:
> On 2012-03-14, David J Taylor<david-taylor at blueyonder.co.uk.invalid>  wrote:
>> "unruh"<unruh at invalid.ca>  wrote in message
>> news:I1T7r.36416$L12.35279 at newsfe23.iad...
>> []
>>> Did you shut down and restart your computer? Did you perchance do this
>>> during the daylight savings time transition on a Windows system? Could
>>> the error be related to the fact that Windows like time on localtime not
>>> UTC?
>> Windows uses UTC internally, not local time.  Local time is simply a
>> presentation layer issue.  Windows is unaffected by a DST transition.
> That must be new, since windows certainly used to maintain system time
> as local time. Caused numberous headaches for people using both Windows
> and Linux.

Windows expects the CMOS BIOS clock to be in local time (which is the 
opposite from Linux), but then converts this twice: First to UTC in 
order to be able to use the NTP protocol, and to timestamp file updates 
with UTC, but then it converts back to local time for almost all 
timekeeping functions.

There is a Registry key which is supposed to allow Windows to use UTC in 
CMOS, but the only time I tried this (many years ago) it was somewhat 

- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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