This Warning event indicates that the configuration domain controller that is mentioned is not running or not reachable. If other Exchange services, such as mail submission, transport, and replication start without errors, this warning can be safely ignored. However, if other Exchange services cannot start, see User Action.

To resolve this warning, do one or more of the following:

• Make sure that the domain controller specified in the event description is correctly registered on the DNS server. For more information about how to troubleshoot DNS issues, see DNS Troubleshooting.
  
  
• If DNS suffixes are specified on Advanced TCP/IP Settings, make sure that the FQDN of the domain that contains the DNS server is listed first. To verify this, do the following:
  
  
  1. In Control Panel, double-click Network and Sharing Center.
     
     
  2. Click Change adapter settings.
     
     
  3. Right-click Local Area Connection, and then click Properties.
     
     
  4. Double-click Internet Protocol Version 4 (TCP/IPv4).
     
     
  5. Click Advanced.
     
     
  6. In the Advanced TCP/IP settings dialog box, select the DNS tab. If there are any entries under Append these DNS suffixes (in order), make sure that the FQDN of the domain that contains the DNS server is listed first.
     
     
  7. Repeat steps 4 through 6 for Internet Protocol Version 6 (TCP/IPv6).
     
     
• If you are using a BIND DNS server, try using a Windows DNS server.
  
  
• Make sure that the Exchange Servers group is added to Manage auditing and security log under User Rights Assignments on the default domain controllers security policy. To verify this, do the following:
  
  
  1. Open the Microsoft Management Console and add the Group Policy Management Editor snap-in. Then, click Browse and select Domain Controllers from the Domains, OUs and linked Group Policy Objects list. Click OK twice and then click Finish. Click OK to close the Add or Remove Snap-ins window.
     
     
  2. In the console tree, expand Local Computer Policy, Windows Settings, Security Settings and Local Policies. Under Local Policies, click User Rights Assignments.
     
     
  3. In the results pane, double-click Manage auditing and security log. Verify that the Exchange Servers group is listed.
     
     

If you are not already doing so, consider running the Exchange tools created to help you analyze and troubleshoot your Exchange environment. These tools can help make sure that your configuration aligns with Microsoft best practices. They can also help you identify and resolve performance issues, improve mail flow, and better manage disaster recovery scenarios. To run these tools, go to the Toolbox node of the Exchange Management Console. To learn more about these tools, see Managing Tools in the Toolbox.