|Message:||Process %1 (PID=%2). Exchange Active Directory Provider received a request to connection to domain controller %3 but that domain controller is not available. Use the Ping or PathPing command-line tools to test network connectivity to local domain controllers. Run the Dcdiag command line tool to test domain controller health.|
This Error event indicates that the domain controller specified in the event description is not working or not reachable. The Active Directory® provider maintains a pool of connections to the available domain controllers. Any Exchange process that has to access Active Directory uses an available connection from the connection pool. This event may occur if the connection in the connection pool indicates that the domain controller is not working or not reachable.
To resolve this error, do the following:
If this error persists, review the Application log and System log on the domain controller and Exchange server for any corresponding Warning or Error events.
If you are not already doing so, consider running the tools that Microsoft Exchange offers to help administrators analyze and troubleshoot their Exchange environment. These tools can help you make sure that your configuration is in line with Microsoft best practices. They can also help you identify and resolve performance issues, improve mail flow, and better manage disaster recovery scenarios. Go to the Toolbox node of the Exchange Management Console to run these tools now. For more information about these tools, see Toolbox in the Exchange Server 2007 Help.