[time] {0,1,2}.<zone>.pool.ntp.org; new monitoring system

Tim Shoppa shoppa
Wed Sep 8 02:36:28 UTC 2004


>  Right now, the monitoring system will be
> biased toward sites in Europe due to lower network jitter and
> latency.  (Does the Net::NTP code deal with the round trip times?)

Actually, with ntpd/ntpq -c peers monitoring having high jitter could
mask a systematic offset.

In any event the +/- 0.5sec tolerance is very very loose.        

And Net::NTP does subtract half the round trip time to account for
symmetrical latencies.

I'd strongly recommend ntpdate -q as well for checking offsets etc.
It makes burst like measurements to get around jitter effects.

> It really isn't that hard to have an ntp server stay within 50ms of true UTC
> now a days.

Mine are within a few microseconds, but not everybody has a PPS clock :-)

Tim.


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