[ntp:questions] NTP not synchronizing to server

Richard B. Gilbert rgilbert88 at comcast.net
Sun Jan 7 23:00:34 UTC 2007


Per Hedeland wrote:

> In article <VbWdna_AErOHmD3YnZ2dnUVZ_uOmnZ2d at comcast.com> "Richard
> B. Gilbert" <rgilbert88 at comcast.net> writes:
> 
<snip>
> 
> I.e. in general, it works just fine to use NTP to synchronize against a
> server that only has its local clock as reference (the quality of the
> time is another thing) - according to the docs it's even "the intended
> use" for the LOCAL refclock, and of course it's quite commonly done. The
> problem here is with the server (non-)implementation.
> 
> --Per Hedeland
> per at hedeland.org

I was under the impression that serving the local clock was intended to 
provide a few hours of "holdover" if the connection to upstream servers 
is lost.  If the local clock has been disciplined by ntpd it should have 
both a correct time and a proper frequency correction that will allow it 
to carry on for a few hours.  How long the time will remain reasonably 
correct would depend on the quality of the local clock, variations in 
the temperature inside the computer case, etc.

ISTR that David Mills added an "Orphan Mode" to ntpd a year or so ago 
that's intended for use on isolated networks that lack a reference clock 
other than the local clock of some computer.  I've never needed it so 
I'm not familiar with how to set it up or exactly how it differs from 
simply serving the undisciplined local clock.




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