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Title
What is the best practice to migrate domains with identical NetBIOS names and is this possible at -
Description
Can my target domain have the same NetBIOS name as the source domain?
Can I migrate two domains with identical NetBIOS names?
What kind of problems can I expect?
Are there any suggestions or workarounds? -
Resolution
When NetBIOS names are duplicate, various problems can arise. The issues would be mostly with the environment, not with the Quest tools.
The issue is applicable for all migrations where the source and target domains happen to have the same NetBIOS names.
The main problem with such a configuration is that it is impossible to set up a trusts between the domains. This makes a co-existence impossible and a migration will have to be performed in one step, when all users and computers are moved to the target domain e.g. over a weekend. In such a case, should a problem arise, there is no easy rollback.
No trusts means that you cannot make the migration gradual. Without trusts, users from one domain (source or target) will not be able to access resources in the other domains. This means that although you can (with Domain Migration Wizard or Quest Migration Manager) migrate the accounts (create target accounts) and re-ACL the resources, you cannot let users start logging into the target domain before all the computers they use (workstations, servers) are moved to the target domain, and you cannot move any computers before all users start logging into the target domain.
Additional information:
NetBIOS requires that NetBIOS names (including the names of domains) are unique. Thus, to make such source and target coexist in the same network, administrators would have to either disable NetBIOS (which is not possible in NT) or put a firewall in place which will filter out all NetBIOS traffic. After that, DNS forwarding could be set up in Active Directory so that resources will be visible.
Even in Windows 2003, trusts still rely on NetBIOS.
This article contains some additional information about the subject: "Understanding NetBIOS and Windows Server 2003":
WindowsDevCenter.com: Understanding NetBIOS and Windows Server 2003 (archive.org)
There are two possible workarounds:
1. For Windows 2003 - renaming a domain (note: you can change a NetBIOS name without changing the DNS name):
Refer to the following Microsoft links for more information:
"Windows Server 2003 Active Directory Domain Rename Tools":
http://www.microsoft.com/windowsserver2003/downloads/domainrename.mspx
"Support WebCast: Microsoft Windows Server 2003: Implementing an Active Directory Domain Rename Operation":
http://support.microsoft.com/default.aspx?kbid=819145
2. Doing a two-step migration with a temporary (third) domain between the source and target domains.