[ntp:questions] Basic Question - How often does Client poll Server?

mayer at gis.net mayer at gis.net
Mon Mar 21 22:32:37 UTC 2005

----- Original Message Follows -----
> At 7:05 AM -0800 2005-03-21, zev wrote:
> >  My question is regarding the amount of traffic the NTP protocol
> >  will generate on the network.  How often does an NTP Client poll
> >  the NTP Server?  Unlike other IP protocols there doesnt seem to be
> >  a fixed timer interval.
>     It depends on the implementation.  In theory, the NTP client 
> should start querying at a short interval initially (on the order of 
> every sixteen seconds or so), but as it gathers more data, it should 
> be able to increase that interval and then maintain a longer interval 
> as it continues to run (on the order of 1024 seconds).

No Brad. The normal minimum, for ntpd only, is 64 seconds and can go up
to 1024 seconds if ntpd decides that everything is stable. If you use
iburst on the server lines then you will get a burst of, I believe,
8 packets sent one after the other to each of the specified servers,
at which point it will settle back to 64 seconds.

This is based on normal operation of ntpd.

>     However, some poor implementations can do really, really bad 
> things, like querying every second -- or worse.  Even with good 
> implementations, it may be possible to mis-configure them so that 
> they behave poorly.
>     So, it all depends on your implementation, and your configuration.
> -- 
> Brad Knowles, <brad at stop.mail-abuse.org>
> "Those who would give up essential Liberty, to purchase a little
> temporary Safety, deserve neither Liberty nor Safety."
>      -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
>      Assembly to the Governor, November 11, 1755
>    SAGE member since 1995.  See <http://www.sage.org/> for more info.
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