[ntp:questions] NTPD silently not tracking

David Lord snews at lordynet.org
Tue Sep 3 06:02:06 UTC 2013


Magnus Danielson wrote:
> On 09/02/2013 02:33 PM, David Lord wrote:
>> Harlan Stenn wrote:
>>> David Lord writes:
>>>> Magnus Danielson wrote:
>>>>> server ntp1.kth.se iburst maxpoll 7
>>>>> server ntp2.kth.se iburst maxpoll 7
>>>>> server ntp3.kth.se iburst maxpoll 7
>>>>> server ntp1.sp.se iburst maxpoll 7
>>>>> server ntp2.sp.se iburst maxpoll 7
>>>> that seems too restrictive and possibly abusive if you do not
>>>> yourself have control over those servers.
>>> iburst is not abusive.
>>>
>>> Perhaps you are thinking of burst?
>> I was thinking about maxpoll 7 and the few stats that were
>> given indicating the very poor reach for the configured
>> servers.
> There is good network connectivity to all 5 servers.
> 
> If you advice us not to use maxpoll 7, then we naturally will learn from
> it. I don't use it personally, but I didn't set this machine up. Would
> be nice to hear your explanation thought.
> 
> However, when doing the ntpdc peers command (in interactive mode), it
> had all 5 servers available, and was tracking one (as indicated with =
> and * at the beginning of the lines, I was told this over phone, so I
> don't have visual memory of it all). So, I don't think bad connectivity
> was the cause. It looked to a non-NTP expert like it had peers, was
> happy with offsets (albeit it looked unexpectedly good at 0) but just
> was plain way off in time.  It took multiples querries with ntpdc peers
> before it reacted on the time-offset, started to display big offsets and
> eventually clean up itself. ntpdate -q did expose the time error of 6 days.

Hi

having a low maxpoll over an internet connection doesn't make
much sense. Variable internet delays are better evened out with
longer poll intervals. Effect of system temperature variations
might demand shorter poll intervals but probably not as low as
maxpoll=7. Having seen one of your recent posts it appears that
some of your sources might be local and under your control in
which case a low maxpoll for them might be understandable.

Without real diagnostics I have no idea what could be the cause
of the problem. I've certainly never experienced a system that
claims to be in sync at the same time as being 6 days off.


David



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