I have been struggling to find out if our disjoint namespace is supported for our exchange 2003 to 2010 transition or guidance on how to fix when the NetBIOS name includes an underscore.

Our single AD DNS domain is called our-domain.com

our NetBIOS name is OUR_DOMAIN

I cannot add OUR_DOMAIN as a dns suffix because of the underscore.

any advice or guidance would be very appreciated.

For any others with a similar setup I have found the following

Research shows that you do not need to fix disjoint namespace when the DNS name uses allowed characters. Exchange 2010 wsp1 will install if the netbios name has and underscore. Links below

Mr. Falk and Mr. Sloan, 
Thank you for asking this question, it pointed out something we need to fix in our docs. 
The NetBIOS name does not have any effect in this scenario. Youll be fine. 
Please take a look at the Scenario 3 section of Understanding Disjoint Namespace Scenarios with Exchange 2007 (http://technet.microsoft.com/en-us/library/bb676377.aspx). The diagram shows a NetBIOS name that has no relation to the domain names in the example.   

The documents should be the same for Exchange 2010 as Exchange 2007. Were updating our Exchange 2010 document to include this information. 

Hello,

If both of the NetBIOS Name and Domain Name have underscore, I am afraid Exchange Server 2010 with SP1 still cannot be installed.

Thanks,

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