[ntp:questions] systems won't synchronize no matter what

Dave Hart davehart at gmail.com
Thu Oct 28 11:52:10 UTC 2010

On Thu, Oct 28, 2010 at 11:07 UTC, Parvin, Richard
<richard.parvin at hp.com> wrote:
> I've noticed that a lot of people use iburst on thier server lines.  I'm wondering why.


As explained on the "Poll Program" page that links to, iburst reduces
the time to initial sync.  ntpd requires three exchanges with a source
to partially fill the 8-sample clock filter register before it will
draw any conclusions.  Without iburst, that means a few minutes at the
default initial poll interval of 64s.  iburst accelerates the process
by sending a series of six requests 2 seconds apart when starting up,
and also after a server has become unreachable.  The first packet must
elicit a response or the rest are not sent.

The visible result when using iburst on all your server lines is it
takes a few seconds instead of a few minutes for ntpd to take the
wheel (and possibly step the clock, if out more than 128ms by

Dave Hart

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