I have search hours from Microsoft documentation and numerous forums but I still can not find a clear answer about disjoint namespaces when NetBIOS domain name is not the same as the subdomain of the DNS domain name. I have DNS domain name "ad.contoso.com" and NetBIOS domain name "contosoad". All existing computers and servers have DNS suffix ad.contoso.com. Do I have to modify msDS-AllowedDNSSuffixes (which is current empty)? Do I have to do anything else regarding this situation? I have already read below articles but have not managed to get a clear undestanding. Understanding Disjoint Namespace Scenarios (http://technet.microsoft.com/en-us/library/bb676377(EXCHG.140).aspx) Exchange 2010 and SLD / Disjoint / Discontiguous Namespaces (http://blogs.technet.com/b/exchange/archive/2009/10/27/3408616.aspx)

Yes you will have to modify/configure the attribute "msDS-AllowedDNSSuffixes" as Mentioned in the article http://blogs.technet.com/b/exchange/archive/2009/10/27/3408616.aspx Gulab | MCTS-MCITP Messaging: 2010 | MCTS-MCITP Messaging: 2007 | MCC 2011 | Skype: Gulab.Mallah

So I add "ad.contoso.com" to msDS-AllowedDNSSuffixes?

Hi, Yes, you need to add. To allow Exchange 2010 servers to access domain controllers that are disjoint, you must modify the msDS-AllowedDNSSuffixes Active Directory attribute on the domain object container. You must add both of the DNS suffixes to the attribute. Hope this helps. ThanksPlease 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.

Hi, Please could you clarify what do you mean by two suffixes?

Hi, They are DNS suffix and DNS domian name. ThanksPlease 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.