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

Harlan Stenn stenn at ntp.org
Wed Aug 8 17:10:11 UTC 2012

unruh writes:
> On 2012-08-08, Arpith Nayak <arpithnayak at gmail.com> 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?
> If the time is out by less than 128msec the procedure will be
> gradual. If it is out by more, ( but less than some 10s of seconds) it
> will suddenly jump. If it is out by even more, ntpd will shut down
> completely (unless you started it with the -g flag and this is the
> first jump).  If you want more continuous behaviour, use chrony.

How is chrony more continuous if it shifts between time sources that

> ntpd makes a great to-do about continuity, but jumps ifthe time is out by
> more than 128ms at any time. That part of ntpd is an incoherent mess. 

One person's signal is another person's noise.

There are tradeoffs involved, I think you know this, and you are
ignoring them.

> (Note that it never slews by more than 500PPM either, unless it jumps (
> infinite PPM). Linux at least has the ability to slew the clock by up to
> 100000PPM (.1 sec/sec) but ntpd does not make use of it. )

And there are tradeoffs here too and you know this and you are ignoring


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