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I have a situation where I have the following setup:

============Primary Network===============
             Bridging Server
=============Secondary Network============

Essentially, the bridging server acts as a firewall and only point of access between two other networks.

None of the machines on the secondary network have access to the wider network, and it is desired that they are all kept closely in sync in terms of time. (+/- 1minute)

I have read about NTP, and believe it may be the route of solving my issues, but I have a couple of queries before I get started...

The bridging server obviously has two NICs, each with its own IP etc.

I want to configure the network so that the bridging server is also a time server, which can get the correct time from elsewhere, then update the computers on the secondary network.

My concerns are thus:

  • If Bridging Server is a time server, could it cause problems on the primary network?
  • This might be a bad way to do things, anybody have any advice?

Also of note, the computers on secondary network are a variety of vintages...from 2000 through XP Pro. The server is XP Pro also (temporarily, will be upgraded to Server 2008R2 soon)

NOTE: I apologise for my shoddy network 'diagram'

share|improve this question
It's really hard to figure out what you're asking. What kind of problems are you concerned about? What do you think might be bad about this? You've stated the textbook, simple/obvious way to get the job done. – David Schwartz Apr 24 '12 at 8:38
I guess I am looking for reassurance. My concern is that there is already another time server on the primary network which I don't want to be in conflict with. I only want the bridging server to act as a time server for my secondary network. How can I limit this? – KingyCronus Apr 24 '12 at 8:43
up vote 2 down vote accepted

If there is a (Windows) time server available in the primary network, you can configure all clients to use that by issuing:

w32tm /config /manualpeerlist:name.of.server /syncfromflags:MANUAL

Followed by

w32tm /resync

On each client.

NTP is perfectly routable, you just have to allow it over the bridge.

share|improve this answer
Thanks. But what does /syncfromflags mean in this case? – KingyCronus Apr 24 '12 at 9:31
w32tm /?. it tells the client to only use the manual peer. – adaptr Apr 24 '12 at 9:31
Many thanks. Accepted. – KingyCronus Apr 24 '12 at 9:32

Sounds fine, although you might want to wait till after you've upgraded to 2008 if that is imminent. It is common for AD servers also to be used as time servers, so you could look at that.

You should probably reboot each client when it starts synchronising time, to avoid any large time jumps affecting running processes and scheduled tasks, especially if those time jumps are backwards. Also bear in mind the effects on any log processing you may perform.

If you already have time servers on the primary network, then you could consider syncing the bridging server to them. You need to consider how important it is to have the correct time as well as the same time.

The ntp clients will only synchronise with the servers you configure.

share|improve this answer
AD doesn't tolerate backward jumps at all – Jim B Apr 24 '12 at 16:55

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