[ntp:questions] Test internal clock

Dave Hart davehart at gmail.com
Thu Mar 19 02:14:22 UTC 2009

On Mar 18, 8:56 pm, "Richard B. Gilbert" <rgilber... at comcast.net>
> Towli wrote:
> > Hi
> > I would like to test my internal clock (from my domain pc) against a
> > public ntp server, to see if there is a discrepance (i suspect our
> > domain time is not synchronised properly).
> > Is there a way to do this?
> You can install ntpd and/or ntpdate.  Ntpdate will either set your clock
> or tell you how far off it is, depending on the options you select.
> Ntpdate is deprecated.

Moreover, ntpdate on Windows is near-useless as it is working with a
15-ms precision OS clock directly.  ntpd synthesizes a timeline using
counters on top of the OS time and is much more accurate as a result.
Of course, w32time is currently setting your domain PC's time and its
also using the limited OS clock.

> Ntpd will discipline your clock so that it synchronizes with your
> selected time source(s).
> Meinberg Funkuhren offers a pre-built ntpd for Windows together with a
> Windows "installer".  Our Meinberg contact is "Martin Burnicki"
> <martin.burni... at meinberg.de>

I think Martin's coworker Heiko Gerstung does most of the Meinberg
installer work.  For the OPs question of comparing his domain PC to
external NTP servers, obviously he's going to need access to UDP/123
to get anywhere as noted.  Once that's working, a relatively easy way
to compare is to setup ntpd with a few sources and enable loopstats
log generation.  Note only one of w32time and ntpd can be active on a
given machine because they both want to listen to UDP/123
exclusively.  Meinberg's installer will disable w32time by default,
I'd suggest letting it do so.  Once you have a working ntpd, stop and
disable the NTP service and enable and start Windows Time service
(w32time).  Come back in a day and reverse the procedure to switch
back to ntpd, and pay attention to the initial loopstats entries to
get an idea of how far off your PC's time is from your selected

Dave Hart

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