[ntp:questions] Why does ntp keep changing my conf file?

John Hasler jhasler at newsguy.com
Fri Sep 17 22:52:38 UTC 2010


Daniel Havey writes:
> So, you think that a PC clock will drift 20-50ms in 5 seconds?

No.  We think that the network latency may jitter tens of milliseconds
in five seconds (especially on a busy network).  Ntpdate will then
erroneously conclude that the clock is off and jerk it around.  You are
trying to track noise instead of filtering it as Chrony and Ntpd do.

> Let me see if I've got this right, you tell me I might get say
> synchronization of ~10ms with ntpd running on a lan with everybody on
> the same switch or perhaps one switch away?

You should be able to do better than 1ms.

> I would actually kind of like to test it myself ;^) But measuring time
> skew between machines may not be as easy as it seems at first glance
> ;^) Surely there must be a paper somewhere that already does this?

You could read Dr. Mills' book...
-- 
John Hasler 
jhasler at newsguy.com
Dancing Horse Hill
Elmwood, WI USA




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