Hi All, I have a parent and child domain in which we are installing Ex 2010 SP1. Can someone clear up for me whether I could create a DAG that contained a member from the parent and a member from the child? I have found slightly older documentation that states they have to be in the same AD domain, but I want to confirm that is still the case. Thanks in advance!!!!!

Yes, DAG members have to be part of the same domain. http://technet.microsoft.com/en-us/library/dd638104.aspx

LMurthy is correct. They can be in different Active Directory sites, but must be a part of the same domain. Further supporting documentation: http://technet.microsoft.com/en-us/library/dd979799.aspx http://technet.microsoft.com/en-us/library/dd979802.aspx