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disp, offset and delay on ntpq output

Posted on 2011-09-06
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Last Modified: 2013-11-17
ok, yes, I'm on 10 things at the same time :-(

here I go:

what is the meaning of disp,offset and delay on ntpq output? It shows differents values..

What is the meaning of a negative value in the offset?

The server is synchronized well. I'm collecting theses 3 data to a chart graph, but I don't understand well the meaning.

Thanks..
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Question by:sminfo
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woolmilkporc earned 500 total points
ID: 36488794
delay = time between request and response

offset = difference between reference time and local (system) time
-- should be clear that this value can be negative

disp = dispersion = jitter = variation of time comparisons

All values are in miliseconds.

wmp
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by:sminfo
ID: 36488912
so,

do I have to worry about this negative values? The varuation of this value says something important?
Or I only have to check that ntpd is sync with external servers?

don't fully understand the "disp"

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by:woolmilkporc
woolmilkporc earned 500 total points
ID: 36489098
Negative offset just means that your time is ahead of the reference time,
positive means that you're behind the reference time.

It's quite normal that there is a difference, otherwise there would be no need at all for synchronizing with an external clock source.

dispersion is interesting if there are several timeservers.
It's then a measure of the overall quality of the mix of time servers you selected.  

If these values indicate just a few tenth of a milisecond (except for "delay" of course!) they're more than normal.
Their display can give you a bit insight in how time synchronization works in your specific environment,
but as long as synchronization finally succeeds - why bother?
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