To resolve this error, perform one or more of the following steps:
Use the Ping or PathPing command-line tools to test basic connectivity from the Exchange server to one of the domain controllers. Use Ping to isolate network hardware problems and incompatible configurations. Use PathPing to detect packet loss over multiple-hop trips. For more information, see Microsoft Knowledge Base article 325487, How to troubleshoot network connectivity problems.
Make sure that all the domain controllers in the domain are registered correctly on the DNS server. For more information, see Microsoft Knowledge Base article 247811, How Domain Controllers Are Located in Windows.
If you have multiple Active Directory sites, make sure that they are configured correctly. For more information, see Creating an Active Directory Site for Exchange Server.
Run the Dcdiag command line tool to test the domain controller health. To do this, run dcdiag /s:<Domain Controller Name> at a command prompt on the Exchange Server. Use the output of Dcdiag to discover the root cause of any failures or warnings that it reports. For more information, see Dcdiag Overview at the Microsoft Windows Server TechCenter.
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.