[ntp:questions] strange behaviour of ntp peerstats entries.

Brian Utterback brian.utterback at sun.com
Wed Jan 30 19:33:24 UTC 2008

David J Taylor wrote:
> Brian Utterback wrote:
> []
>> Which is why NTP prefers the source with the smallest delay. The
>> system I am using has servers whose delays are 51ms to 94. I can't
>> find any closer. On my company LAN, the delays range from 16ms to
>> 87ms. The offsets of all these servers agree to within 9ms. Sure, I
>> am not going to get sub-millisecond from that, but I think it is 
>> probably
>> more typical than your set-up.
>> Brian Utterback
> Brian,
> I know this is supposed to happen, but I recall seeing behaviour some time 
> ago where a server with a little more jitter and much more delay was 
> preferred, almost as if it was the jitter/offset which was the measure 
> rather than offset itself.  I ended up adding a "prefer" qualifier.
> Cheers,
> David 

I mis-spoke. It is actually the case that NTP prefers the sample of
the eight from any one single source that has the least delay. After
the sample is chosen, the samples from all the servers are then
subjected to different criteria to determine which will be the final
choice. Jitter and stratum both factor in.

Brian Utterback

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