[ntp:questions] NTPD can take 10 hours to achieve stability

Chuck Swiger cswiger at mac.com
Mon Apr 18 23:25:48 UTC 2011


On Apr 18, 2011, at 2:54 PM, C BlacK wrote:
> Thanks for all the great answers.  Now for a harder question, how does the accuracy of the local clock source affect the accuracy of ntpd.

Normally, except for stratum-1 NTP servers which are specifically configured to use a high-quality local timesource (ie, GPS, ACTS, WWV, atomic clocks, etc), the local clock isn't used at all.  For stratum-2 and higher timeservers, ntpd will pick the most accurate timeserver based upon a selection algorithm, and discipline the kernel clock against that as the reference.

On many platforms, the kernel clock will periodically be written out to the system RTC (aka TOD/TOY clock) used to keep time when the system is powered off.

Regards,
-- 
-Chuck




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