[ntp:questions] pps coming in, not received by ntpd

David Taylor david-taylor at blueyonder.co.uk.invalid
Mon Jul 1 15:50:33 UTC 2013

On 01/07/2013 14:37, folkert wrote:
> I think PPS because that's the most accurate source in my situation I
> think. The nmea source jitters all over the place
> But I don't think the prefer keyword doesn't change anything if pps
> comes in or not?
> Folkert van Heusden


My understanding (and I hope others will correct me if I'm wrong) is that:

- if you have a PPS source you also need a source of time (to get the 
nearest second), and the best source of time data is the one you should 
mark as "prefer".

- if you have no PPS source, then if NTP sees two or more servers as 
equally good "prefer" will cause NTP to select one over the other.  this 
could help where you have two equally good servers and NTP hops between 

I suspect that the operation is actually the same with or without a PPS 
source, and the usage of the keyword depends more on circumstances than 
on the function you get.
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