Accepted Solutions
Using snapshots and clones with AD VMs (i.e. domain controllers) can be done (I've done it when, for example, testing schema changes) but be very careful how you do it.
The main problem is that if you start randomly reverting to snapshots, the update sequence numbers AD uses to keep track of the changes made on each DC will get screwed up - you'll probably have problems with DCs not replicating changes etc.
If you really have to do it, take every DC down, then take a snapshot of each one. Bring them back up, make your changes or whatever then when you're ready to revert to snapshot, take them all down again and revert to the snapshots you took at the start. Don't power anything up until all the snapshots have been restored. You should find that is ok.
You would have to be absolutely flippin' insane to start doing this in your production AD though - if you're tempted, put the keyboard down and step AWAY from the DC.
Good luck! 
as I said too much pain 
Although in a sandboxed test environment it can be done but never in a production environment, as said if you ever get the urge, put you keyboard down and dip your head in a bucket of cold water until sanity returns.
Tom Howarth
VMware Communities User Moderator