[ntp:questions] Polling time backoff

Richard B. Gilbert rgilbert88 at comcast.net
Sun Nov 29 01:29:26 UTC 2009


shane-dated-2009 at csy.ca wrote:
> Hi,
> 
> Just wondering if there is anything in particular which would keep ntpd
> polling its servers every 64s. I thought it was supposed to backoff to 1024s
> eventually but this doesn't seem to be the case here.
> 
> continuum:~$ ntpq -p
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> *GPS_NMEA(0)     .GPS.            0 l    9   16  377    0.000   -0.006   0.001
> +dns1.uniserve.c 140.142.16.34    2 u   43   64  377   10.898    2.437   1.734
> -dns2.uniserve.c 131.188.3.220    2 u   50   64  377    9.005   -1.581   3.804
> +time.nrc.ca     132.246.168.2    2 u   24   64  377   72.240    1.565   5.935
> 
> My ntp.conf is pretty boilerplate save the following bits.
> discard average 30
> discard minimum 3
> 
> restrict default kod limited nomodify notrap nopeer
> restrict 127.0.0.1
> 
> server 127.127.20.0 minpoll 4 prefer
> fudge 127.127.20.0 flag3 1 flag2 0
> 
> The other servers are just server xxx iburst
> 
> Isn't 64s too short a polling time? ntp version is 4.2.4p6 (Debian).
> 
> Best,
> Shane

NTPD adjusts its polling rate to fit the conditions.  If it is polling 
at 64 second intervals forever, it is not happy with the quality of time 
that it's getting from those upstream servers.

You might find it interesting to look at the output of ntpq in the early 
morning hours, say between 0100-0600 local time.  The net is much 
quieter during those hours and ntpq shows that ntpd is happier with the 
quality of time its getting.  If it's still locked at 64 seconds further 
investigation may prove fruitful.




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