A. After you've upgraded an NT-based domain to Active Directory (AD), you should be able to use either the domain's NetBIOS name (e.g., savilltech) or its DNS name (e.g., savilltech.com) to join computers to the domain. If you can join a computer to the domain only by using its NetBIOS name, an incorrect DNS configuration might be the source of the problem. You can check a system's DNS configuration by entering the following lines at the command prompt. (The text that's enclosed in quotes represents messages that are displayed after you type the indicated commands.)

nslookup
"Default Server: omega.savilltech.com
Address: 10.0.0.1"

set type=srv
_ldap._tcp.savilltech.com
"Server: omega.savilltech.com
Address: 10.0.0.1"

"_ldap._tcp.savilltech.com SRV service location:
priority = 0
weight = 100
port = 389
svr hostname = omega.savilltech.com
omega.savilltech.com internet address = 10.0.0.1"

exit

Instead of _ldap._tcp.savilltech.com, enter _ldap._tcp, followed by your DNS domain name. If the nslookup command finds DNS records, your system's DNS configuration is probably correct. If nslookup finds no DNS records, check your DNS entries and, if they're correct, check the DNS server itself.

If your DNS configuration is in order, your domain controllers (DCs) might have the NT4Emulator registry entry enabled, which means they're emulating NT 4.0 DCs and thus won't respond to AD-style requests. You can test whether NT4Emulator is enabled on your DCs by configuring the neutralize NT4Emulator option on the client you're trying to join to the domain:

  1. Start the registry editor (regedit.exe).
  2. Go to the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetlogonParameters subkey.
  3. From the Edit menu, select New and click DWORD Value.
  4. Enter the name NeutralizeNT4Emulator and press Enter.
  5. Double-click the value and set it to 1. Click OK.
  6. Close the registry editor.

You don't need to restart the computer or log off; just try again to join the computer to the domain by using the DNS domain name. If the computer joins the domain successfully, you must either disable the NT4Emulator on the DCs or configure the NeutralizeNT4Emulator value on all machines on which you want to use the DNS name for the domain.