Hi, We are going to setup a Multi Tenant/Hosted Exchange 2010 and I was wondering what kind of licenses we will need. To start with we are going to setup one AD server (Windows Server 2008 R2) and two Exchange servers in a DAG and later on add one more to the DAG. We are going to have this as a complement to our other services and are hoping to get a couple of hundred users/mailboxes over to this service. What kind of licenses do we need? One more question: Is there a way to cluster two AD servers? I'm new to Windows servers as I'm usually a *NIX administrator. But just having One AD server and cluster the rest seems pretty pointless to me because if the AD server goes down everything goes down. And if so, is it possible to start of with one AD server and then later on cluster them without to much hassle? Thanks, -Patric

HI Patric, You can directly contact Microsoft support to get detail about Licencing for hosted exchange or HMC. Regarding your query about AD cluster, there is not such feature to install cluster for AD. AD itself work in form of cluster (thru replication) once you install second Domain controler as peers in same site. You can see below KB article and can post any question in active directory forum. http://technet.microsoft.com/en-us/library/cc733027(WS.10).aspx Anil

ah thanks for the info! And we contacted Microsoft and we now know exactly what kind of license we need.

By the way, there is a dedicated forum for Hosted Exchange 2010. http://social.technet.microsoft.com/Forums/en-US/exchange2010hosters/threadsPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.