[ntp:questions] Remaining synced on an unsynchronised peer?

Richard B. Gilbert rgilbert88 at comcast.net
Mon Nov 30 21:21:37 UTC 2009

Michael Butow wrote:
> On Mon, 30 Nov 2009 15:24:03 -0500, Richard B. Gilbert wrote:
>> "Historical Reasons" is a pretty feeble excuse.  NTPD will, if permitted
>> to do so, adjust that polling interval as needed to get the most
>> accurate time.  By pegging minpoll and maxpoll you are crippling the
>> ability of NTPD to get the greatest possible accuracy.
> I'll clarify this point (which I think is not relevant to my issue 
> though):
> The system doesn't need the greatest possible accuracy, it is more 
> important to the users to detect loss of time sources quickly.
> Also, this setting was used in the past in the presence of components 
> which were causing loss of time interrupts, and the clock was not 
> controllable in another way.
> I'd still appreciate any comments to my actual question ;-)

NPTD is aware when a time source is not responding.  If other sources 
are configured NTPD will use them.  Normally, you would configure four, 
five, or seven servers which would protect you from the failure of one, 
two, or three servers.  Here, "failure" refers to either "not 
responding" or to "insanity"; e.g. a grossly incorrect time.

A fairly simple script run at intervals of, say, ten minutes could 
determine that NTPD had lost contact with enough servers to impair its 
ability to determine the correct time.  The script would then send a 
text message to someone's cellular phone and that someone would take 
whatever action was required.

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