[ntp:questions] Re: SNTP Client/Server questions

Hal Murray hmurray at suespammers.org
Wed Aug 16 18:56:28 UTC 2006

>thanks.  We aren't looking for performance extremes...  Would it be
>reasonable to get an accuracy within several seconds, feeding sntp
>clients on a lan from an sntp server which itself was fed from an NTP
>server on the net?  Assuming a local clock which is nominally 60 ticks
>per second?  And assuming the polls on both ends could be done often
>enough to account for local clock drifts?

That depends on how often you poll and how much your clock drifts.

"several seconds" is a long time relative to round-trip delays to
a nearby time server.  Let's ignore those delays for now.

Several PCs I have access to are off by slighly more than 100 ppm.
There are 86K seconds per day.  Call it 100K.  So a crystal error of
10 ppm would turn into a clock error of one second per day.

So you would have to poll 10 times per day - once every 2 hours.

Back to network delays.  Does your link to the outside world get
overloaded at times?  That may confuse things.

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