Topic Last Modified: 2008-11-17

The Microsoft Exchange Analyzer Tool queries the Active Directory directory service to determine the value of the ComputerNameDnsHostname attribute. The value of the ComputerNameDnsHostname attribute represents the fully qualified domain name of the destination computer.

If the Exchange Analyzer determines that the Domain Name System (DNS) domain name set on the local computer is invalid, the Exchange Analyzer displays an error.

This error means that the DNS domain name contains characters other than 'A-Z', 'a-z','0-9', '.' and '-'.

To resolve this issue, determine whether the invalid characters are in the local computer's machine name or the actual DNS domain name.

To verify the DNS domain name of the local computer
  1. Right-click My Computer, and then click Properties. The System Properties dialog box will appear.

  2. Click the Computer Name tab.

  3. Click Change. The Computer Name Changes dialog box will appear.

  4. Click More. The DNS Suffix and NetBIOS Computer Name dialog box will appear.

  5. Verify that only characters in the range of 'A-Z', 'a-z','0-9', '.' and '-' are used.

  6. Select the Change primary DNS suffix when domain membership changes check box.

  7. Click OK to save any changes, and then click OK to exit the Computer Name Changes dialog box.

  8. Click OK to close the System Properties dialog box, and then restart the computer for any changes to take effect.

For more information about DNS names, see Microsoft Knowledge Base article 909264, "Naming conventions in Active Directory for computers, domains, sites, and OUs" (