[ntp:questions] Re: HowTo calibrate system clock frequency using NTP

David L. Mills mills at udel.edu
Wed Feb 1 03:44:50 UTC 2006


Looks like you have a sign reversal. Better recheck your math.

The ntpdate is deprecated and replaced by sntp in recent versions. I 
hear it was eaten by a Grue and if you know what that means, you have 
some idea how ancient ntpdate had become.


Daniel Kabs wrote:

> Hello Professor Mills,
> now I have a plan :-) Thank you.
> I copied your valuable instructions into the NTP wiki at
> https://ntp.isc.org/bin/view/Support/HowToCalibrateSystemClockUsingNTP
> I wonder why your procedures do not use "ntpdate". Is it because 
> "ntpdate" is to be retired soon from your ntp distribution? Or will 
> "ntpdate" fail to provide data as precise as ntpd? Indeed, I see a 
> difference when I compare the drift file value against the offset 
> measured by ntpdate:
> A) I had ntp running for one day against a time server. The value in the 
> drift file converged monotonously to -268.173. This gives a clock error 
> of -23.17 s/day.
> B) I configured ntp in order to serve the pseudo local clock. I 
> periodically measured the time offset from a time synchronized PC using 
> "ntpdate". A least-squares fit gives a slope of 23.87 s/day.
> Any idea why is this?
> Cheers
> Daniel

More information about the questions mailing list