[ntp:questions] Synchronizing against a free-running server

detha detha at foad.co.za
Mon Apr 15 17:38:28 UTC 2013

On Mon, 15 Apr 2013 17:01:50 +0200, Jeroen Mostert wrote:

> On 2013-04-15 11:40, detha wrote:
>> We have been trying to convince ntpd to synchronize with a free-running
>> windows server (why one would want to do this is another question,
>> suffice to say there are political reasons).
> I'm sort of curious what reasons those could be. Is the Windows machine
> the domain controller and do people think that syncing with it is better
> than not syncing with it?

Site with no reliable external comms. There have been cases with similar
sites that were solely on VSAT where the interface with the outside world
consisted of a USB external harddrive that got driven back and forth to a
nearby (~100 miles) site daily for over a week.

A bunch of Win7 PCs and embedded systems, W2K8 PDC, and one or two Linux
boxen. One needs to be able to match timestamps in logfiles between

> This is sort-of true, even, although this set-up is really weak. Even
> so, in my experience, having ntpd clients sync with a w32time server is
> still not as bad as the other way around. The best set-up is ntpd all
> the way, of course, whether you sync with external time or not. Even
> sync to within 1 second is not something w32time can promise (although
> that's probably more a problem on the client side than the server side).
> The next logical step might be sneaking ntpd onto the Windows server. It
> performs fine, especially on Windows Server 2012/W8. Installing ntpd on
> all Windows clients could be a bit more involved.

Putting ntpd on the PDC is probably an option. All clients? Not so much.
Having a timesource with a GPS receiver would be better. What gets chosen
in the end depends more on internal politics and financial issues than on
sound technical reasons.

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