[tz] Leap seconds puzzle

Paul_Koning at dell.com Paul_Koning at dell.com
Wed Apr 8 19:46:39 UTC 2015

> On Apr 8, 2015, at 3:17 PM, Steve Allen <sla at ucolick.org> wrote:
> On Wed 2015-04-08T19:02:07 +0000, Paul_Koning at dell.com hath writ:
>> So here is the puzzle.  I would expect WWV, and www.time.gov, to
>> reflect leap seconds.  So why would they give me a time that matches,
>> to the second, the POSIX time on my workstation?  Does NTP send POSIX
>> seconds since epoch rather than real ones?
> NTP effectively sends "mean solar seconds elapsed since epoch", which
> is another way of saying "elapsed seconds not counting leap seconds"
> as is demanded by POSIX.

Thanks much!  That sure is not clear from the RFC.  So that explains things: it means that a POSIX system that is an NTP client will track UTC, leap seconds and all, except for a short while just after a leap second occurrence because at that point the NTP client machinery will be adjusting to the one second phase shift.


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