[ntp:questions] Does NTP cause an abrupt/sudden change in an orphan's system time?

Richard B. Gilbert rgilbert88 at comcast.net
Wed Aug 8 22:46:15 UTC 2012

On 8/8/2012 6:56 AM, Arpith Nayak wrote:
> I have a server that is in the orphan mode i.e. it was not connected to the
> internet (and thus the various public NTP servers) when I booted it up. Now
> if I install ntpd oin this server and run it, will the first instance of
> ntpd cause a sudden change in the system time as well as timestamps or does
> NTP cause a slow gradual change so that it syncs up with the public server
> over a period of time?
> Regards,
> Arpith

If the clock is seriously in error NTPD will step the clock.  If the 
clock  is very close to being correct, NTPD will adjust the speed of the
clock to make the change slowly.  I don't recall how far off the clock 
must be before NTPD will step it.  It might require as much as 10 hours
for NTPD to synchronize.  ISTR it takes a minimum of thirty minutes from
start up until it has a reasonable facsimile of the correct time.  It 
could take another nine and a half hours to get the correct time AND a 
stable clock.

It should be obvious that NTPD needs to run 24x7 for best results

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