[ntp:questions] Beginner needs help...

Dave Hart davehart at gmail.com
Wed Mar 2 09:05:29 UTC 2011

On Tue, Mar 1, 2011 at 07:10 UTC, Robert Hegner <robert.hegner at hsr.ch> wrote:
> Thanks Chris and Dave for your answers.
> I think I should give some more information about the computer I want to use
> as time server. This computer has two network interfaces. One is for the
> mentionned local network and using the other one it is connected to the
> company network and internet.
> My first attempt was to synchronize this computer to a set of public time
> servers. This didn't work because this system synchronizes its time with the
> domain, and domain policies do not allow the NTP service to set the time.
> This is why I changed the config file of to use the local clock
> (and therefore the domain time) as reference. Isn't this the same situation
> as if I used a radio clock as a reference on this system?

It sounds like you think's clock is being controlled by
the domain, but it's not if you're running ntpd as you described.  The
Meinberg installer disables the W32Time (Windows Time) service which
is the agent that keeps your clock in sync with the domain.  W32Time
and ntpd can't coexist on a single machine, as they both use the NTP
protocol and listen on UDP port 123.

> So since I want the same time on all three computers and since I cannot
> modify the clock of, it was the obvious solution for me to use
> that computer as the (single) time server in my setup.

You may not have permission to modify the clock, in which case you
might uninstall NTP and re-enable the Windows Time service, and your
other two machines will sync to Windows Time.  You'll probably need
"tos maxdist 20" or so in the ntp.conf of machines pointed to a
W32time source, as W32time polls upstream sources very infrequently,
perhaps once a day in a domain setup (and once a week otherwise).

> Would my setup work better if only I used WinXP on, or is using
> the domain time as a reference a bad idea anyway? (I don't know what
> mechanism is used to synchronize my computer to the domain time, and I don't
> know what the reference for the domain time is...).

How tight is your synchronization requirement among these three
machines?  That makes a big difference in which solutions will work.

Dave Hart

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