underscore character in domain name

If your Active Directory name will mimic the DNS namespace that is published to the Internet, the following rules would be in effect in accordance with RFC 1123:

"In general, a domain name can consist of only letters (a to z), numbers (0 to 9) and dashes/hyphens (-). Other characters are not allowed for technical reasons. The name cannot start or end with a dash and there is a maximum length of 80 characters. Domain names are not case sensitive so it's OK to mix cases for reasons of clarity. The name of the HTML file (after the domain name) is not supposed to be case sensitive, but it is on many servers."

For further information on allowed characters in Windows 2000 DNS, you may check here:

http://www.microsoft.com/resources/documentation/Windows/2000/server/reskit/en-us/Default.asp?url=/resources/documentation/Windows/2000/server/reskit/en-us/cnet/cncf_imp_xvxz.asp

Essentially the answer is that the underscore character will not be allowed if you are seekign to meet RFC complaince.

Thanks for that link. My internal namespace won't be used on the outside so I think this means I should be safe with the underscore.

It looks like I just need to select the option for UTF8 on the DNS server.

If I were to change the domain name to eliminate the underscore, would simply changing the domain on the PDC then on any BDCs allow my users to logon to the new domain name without effecting any ACLs?

I assume I would need to join the machines all over again. Is this correct?

Thanks Again for any help