[ntp:questions] making sense of stats offset values [or trying to...]

David J Taylor david-taylor at blueyonder.not-this-part.nor-this.co.uk.invalid
Tue Apr 28 07:23:45 UTC 2009


David Woolley wrote:
> David J Taylor wrote:
>> David Woolley wrote:
>>> Bruce Lilly wrote:
>> []
>>>>        # ntpq -p
>>>>             remote           refid      st t when poll reach  delay 
>>>> offset  jitter
>>>>         *megatron.blilly 18.26.4.105      2 u   27   64  377
>>>> 2.927    0.296   0.122
>>>>         # ntptrace
>>>>         megatron.blilly.net: stratum 2, offset 0.002120, synch
>>>> distance 0.024161
>>>>
>>>>        Note that ntpq reports an offset of 0.296 milliseconds from
>>>> the local host to its system peer, while
>>>>        ntptrace reports an order of magnitude larger offset!
>>>
>>> 2.120 milli-seconds is not an order of magnitude different.  I think
>>>  you are expecting milliseconds to have three zeros after the
>>> decimal point; they don't!
>>
>> David,
>>
>> I'm missing something here - how are 0.296ms and 2.120ms not about
>> "an order of magnitude different"?
>
> My mistake. I looked at the decimal point on the delay; it wrapped to
> the start of the line.
>
> However, as noted, that is the difference between a one shot
> measurement and a filtered one.

Thanks, David.  I found your explanations most helpful, so thanks for 
those.

Cheers,
David 




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