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

Richard B. Gilbert rgilbert88 at comcast.net
Mon Apr 18 12:19:33 UTC 2011

On 4/17/2011 10:58 PM, C BlacK wrote:
> Why would it take ntpd ten hours to achieve its accuracy?  Can this be explained in laymans terms and
> mathematically
>>> Absolutely normal!  NTPD can sometimes need up to ten hours to achieve
>>> the accuracy it is capable of.

And the answer is. . . .

"Mills, David L. Network Time Synchronization: the Network Time Protocol 
on Earth and in Space, Second Edition, CRC Press 2011, 466 pp."

If you are unable to follow Professor Mills' math you'll just have to 
take it "on faith".

Empirical evidence suggests that he's right; it works!

There is a program called "chrony" that converges quickly.  I suspect 
that it must sacrifice something to obtain the fast convergence.

Those who care about the correct time tend to run their clocks 24x7

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