periodically overridding NTP for simulation purposes

I have this situation:

• NTP is used to sync time on a set of Windows 7 and Server 2008 machines. Nothing out of the ordinary about this.
• periodically on this system, the time needs to be changed for testing/training purposes (it is a training simulation system that has a lot of time-dependent operations).

My question:

As NTP in general does not really like big time jumps or changes AFAIK, is there a standard way this could be set up to allow the clock to be changed at the root NTP server in the system and have it propagate through the system in a reasonable amount of time (a minute or two?) It is not acceptable to disable and/or restart all NTP client services to achieve this.

Any ideas? It would be nice to do this without writing some kind of custom script to disable services and update clocks all over the place.

Thanks in advance.

Solution 1:

How about isolating this group of time-travelling machines and pointing them to a dedicated NTPD service on a server with some spare resources?

There are NTP commands available to make/allow big NTP jumps, so you can either push them out over the network or embed them as local commands in your training simulation system/scripts?

Or disable NTP on these machines altogether and obtain complete set time/date freedom?