[ntp:questions] Isolated Network Drift Problem

Maarten Wiltink maarten at kittensandcats.net
Tue Nov 25 08:25:10 UTC 2008

"Cal Webster" <cwebster at ec.rr.com> wrote in message
news:1227558472.16996.100.camel at inet3...
> What's the best way to determine which of our NTP servers provides the
> best local clock?

First order: reset drift (delete all their drift files), synchronise their
watches, let them run for a few days, and see which one has drifted least.
Correct for drift.

This depends on how well you can put them all in the same starting state
by hand, and on the time source you use to measure drift at the end. You
can correct for the former by waiting longer. You _cannot_ outwit your
dependency on the latter.

Second order: after the previous procedure, they should all drift very
little, and no one significantly more than any other. The one that stays
closest to that time source you're comparing against has 'the best local
clock'. This depends mostly on temperature stability.

Maarten Wiltink

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