Note: Its a test server with only half a dozen users so no rush to fix.
gjm: I think I read that you can reset the computer account for the failed exchange server and then just do a reinstall on a fresh machine (call it the same thing and then join to domain). Exchange stores a lot of its config in AD so it can retrieve it all from there. Prob pay to read up on this a bit before starting though as its something I glanced over. Might have been only for Exch 2010 as well...not sure what version you are running.
lyonrouge: ps. Exchange Server is a VM.
gjm: um, taking snapshots of Exchange servers is not really a good idea although in a lab like this I guess it would be better than nothing. If you want to see a mess snapshot a Exchange DAG member, let them go for a day or 2 and then restore the snapshot. Snapshotting AD would be an even worse idea (although apparently svr 2012 has some features that account for fresh grad / domain admin combination).
lyonrouge: Looks similar to the scenario you described. I put the RODC in the internal network, then added another code in the edge, then removed the internal adapter, and somewhere around here all hell broke loose and the Exchange server went offline.
I think it has much more to do with Hyper-V virtual networking that it does with RODC.