You Cannot Start the Active Directory Users and Computers Tool Because the Server Is Not Operational

Any of the following symptoms may occur:

• When you try to start the Active Directory Users and Computers tool, you receive the following error message:
  Naming Information cannot be located because:
  The Server is not operational.
  Contact your system administrator to verify that your domain is properly configured and is currently online.
• When you try to start the Active Directory Sites and Services tool, you receive the following error message:
  Naming Information cannot be located because:
  The server is not operational.
  Contact your system administrator to verify that your domain is properly configured and is currently online.
• When you try to start the Active Directory Domains and Trusts tool, you receive the following error message:
  The configuration information describing this enterprise is not available.
  The server is not operational.
• Logon processing is very slow.
• If you have multiple domain controllers, you can connect with the Active Directory Users and Computers tool to another domain controller that has port 389 open without receiving an error message. But you cannot access a domain controller until port 389 is opened.

These issues may occur if TCP/IP filtering is configured to permit only port 80 for TCP/IP traffic.

Port 389 is used for Lightweight Directory Access Protocol (LDAP) connections. This port is blocked if TCP/IP filtering is configured incorrectly. By default, TCP/IP filtering is configured with the Permit All setting. To verify and correct this setting:

1. Right-click My Network Places on the domain controller on which you cannot start Active Directory Users and Computers, and then click Properties.
2. Click Internet Protocol, and then click Properties.
3. Click Advanced.
4. Click Options.
5. Click TCP/IP Filtering, and then click Properties.
6. For the TCP/IP Port setting, click Permit All.
7. Restart the computer. This opens all TCP ports, including port 389.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

For additional information about TCP/IP filtering, click the article number below to view the article in the Microsoft Knowledge Base: