Process %1 (PID=%2). All Global Catalog Servers in forest %3 are not responding: %4

This Warning event indicates that DSAccess component on the Exchange server found no global catalogs suitable for LDAP queries. This can cause mail flow to stop. It can also cause problems with the address book services. It should be investigated immediately. This warning may be caused by the following conditions:

• DSAccess found no suitable global catalogs when initial topology discovery was done.

• Network problems have rendered global catalog servers unreachable.

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

• If you can, make sure that you have at least two domain controllers in a site that is configured with global catalog servers. This is for failover purposes.

• Check the Application log for related events. The detail in other MSExchangeADAccess events and other events may help determine the root cause of this warning. Increase diagnostic logging for the MSExchangeADAccess\Topology category to Minimum or higher.

  • To review the current MSExchangeADAccess service diagnostic logging settings, in the Exchange Management Shell, type Get-EventLogLevel MSExchangeADAccess.

  • To change the logging level for the Topology category, in the Exchange Management Shell, type Set-EventlogLevel MSExchangeADAccess\Topology -Level Minimum.

• If MSExchangeADAccess Event ID 2080 is logged, no suitable global catalogs were found when initial topology discovery was completed. Review that event to determine which domain controllers have been contacted and if they are unsuitable for any reason. Correct any problems as indicated by the Event description. For more information, see Microsoft Knowledge Base article 316300, Event ID 2080 from MSExchangeDSAccess.

• If MSExhchangeADAccess Event ID 2070 is logged, a global catalog may be down or is unreachable. Review the event to get details about why each domain controller has become unsuitable. ADAccess found no suitable global catalogs when initial topology discovery was completed.

• Use the Ping or PathPing command line tools to test basic connectivity. 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.

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.