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

David J Taylor david-taylor at blueyonder.co.uk.invalid
Sun Mar 18 11:01:00 UTC 2012

"Ron Frazier (NTP)" <timekeepingntplist at c3energy.com> wrote in message 
news:4F65006D.4090205 at c3energy.com...
> Come to think of it, my comment about the polling interval not 
> increasing may only apply to a local refclock, not a local server.

You may be right - all the servers on this test system are Internet 

> Can you elaborate more about what NTPD_USE_INTERP_DANGEROUS does?
> Sincerely,
> Ron

Overnight results are here:


As you can see, jitter is under a millisecond, with the local (noselect) 
server showing about half a millisecond of jitter, and the Internet 
servers between about 3 and just over 6 milliseconds.

NTPD_USE_INTERP_DANGEROUS if set, forces interpolation on Windows.  With 
Windows XP or earlier, Interpolation works well, but not on Vista or 
later, so under certain conditions, NTP disables interpolation as 
mentioned here:


You can enable interpolation, and you may get better results.  If not, 
jitters will have a floor of about 0.977 milliseconds.


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