This Warning event indicates that the Microsoft Exchange File Distribution service could not connect to the remote server that is specified in the event description. The File Distribution service synchronizes offline address book (OAB) files between Exchange servers that have the Mailbox server role and the Client Access (CAS) server role installed if the Mailbox server is using the ExchangeOAB file share. This event may occur if the ExchangeOAB file share is not available or the server that has ExchangeOAB file share is down.

To resolve this Warning event, follow these steps:

• Make sure that the remote server that is specified in the event description is working correctly. You can also use the Ping or PathPing command-line tools to test basic connectivity. For more information, see Microsoft Knowledge Base article 325487, Advanced network adapter troubleshooting for Windows workstations.
  
  
• Make sure that the Windows Server service on the specified remote server is running. You can use Windows Services console to verify this step.
  
  

Make sure that ExchangeOAB file share on the specified remote server can be accessed from the Exchange server that logged this event.

• Review the Application log and System log on your Exchange 2010 servers for related events. For example, events that occur immediately before and after this event may provide more information about the root cause of this error.
  
  
• Review the Operations Console in Operations Manager for detailed information about the cause of this problem. For more information, see the "Introduction" section in this article.
  
  
• Resolve your issue by using self-support options, assisted support options, and other resources. You can access these resources from the Exchange Server Solutions Center. From this page, click Self-Support Options in the navigation pane to use self-help options. Self-help options include searching the Microsoft Knowledge Base, posting a question at the Exchange Server forums, and others. Alternatively, in the navigation pane, you can click Assisted Support Options to contact a Microsoft support professional. Because your organization may have a specific procedure for directly contacting Microsoft Technical Support, be sure to review your organization's guidelines first.
  
  

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.