[ntp:questions] Re: Time sync over bad modem line

Nagy Bela belus at petra.hos.u-szeged.hu
Wed Oct 27 16:38:10 UTC 2004

Thanks for your help.

> NTP cannot really synchronize your clock with an intermittent connection 
> of poor quality.  What you can do is SET your clock whenever you connect 
> to the internet;  ntpdate is good for this.  One or two phone calls a 
> day could keep your clock within a few seconds of the correct time.
What if the delay is over a second? Can ntpdate handle this?
(Sometimes it happens.)

> In order to work as designed, ntpd must query one or more (four are 
> good, five or more better) servers at intervals of, at most, 1024 
> seconds.  The intervals normally start at 64 seconds and increase to 
> 128, 256, 512, and 1024 seconds as the clock synchronizes.  ntpd expects 
> a connection "on demand"; the delay involved in making a phone call each 
> time would introduce a ten or fifteen second error!
Can I change this with maxpoll=minpoll=64 sec? 
Does it help anything?
Because most of the time, this computer is connected to the net only for
10-15 minutes and I would like to have my clock as accurate as possible.

Or a "reverse" question: If my computer is connected to the net for,
say, 15 minutes and we assume nothing about the line (i.e. several second
long delay may occur and this delay may vary widely), then 
how accurately can ntp set my clock?


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