We have an exchange 2007 cluster running on 2 Windows 2008 servers. We have 3 domian controllers, all running Windows Server 2008.Today I discovered that the Forest Function level is Windows 2000 and I am pretty sure this is outside of best practice, best practice for Exchange 2007 being 2003 or higher function level for the forest.My question are:What are the risks I now face if/when I up the function level of the forest?Can I elevate the funciton level to 2008 since all exchange and domain controllers are running 2008?Do I need to worry about our legacy software that runs on 2003 hosts if I elevate to 2008 function level? (none of these hosts are domain or exchange related, just accounting and other database software)Thanks!

I just found out that Forest Function Level of Windows 2000 is ok for Exchange 2007 IF you don't have any domain trusts. Domain trusts require the level to be 2003 or greater. This means I am not in an unsupported configuration as I feared I was.My question about raising the level to 2008 still stands, if anyone can answer it.

What is the upgrade history of your domain? Was it installed as 2008 or did this come from a 2000 domain.Mark Morowczynski|MCT| MCSE 2003:Messaging, Security|MCITP:EMA 2K7,EDA Win 7,ES,SA,EA|MCTS:Windows Mobile Admin|Security+|http://almostdailytech.com

I was recently hired here and don't know the entire history. It has been only on 2008 servers with an AD level of 2008 since I have been here. I asked and was told the first domain controller was probably 2003, with an off chance it was 2000.I bumped the forest functional level to 2008 last night, no adverse effects so far.

Hi,Please note the following sentence: The minimum Active Directory forest functional level for each forest is Windows Server 2003 if one of the following conditions is true: Your topology includes multiple forests that contain Exchange 2007. Your implementation requires a forest-to-forest trust between a forest that contains Exchange 2007 and a forest that does not contain any version of Exchange, such as a forest that contains only user objects. You require a forest-to-forest trust between forests that contain Exchange 2007. Note: In these scenarios, a Windows Server 2003 forest functional level is a requirement. It is not optional. Besides, we notice that Windows 2000 Forest Functional Level is NOT supported for Exchange Server 2007 RTM,SP1,SP2. Exchange Server Supportability Matrix http://technet.microsoft.com/en-us/library/ee338574(EXCHG.80).aspxRegards,Xiu