Topic Last Modified: 2010-02-15

The Microsoft Exchange Server 2010 Management Pack for System Center Operations Manager monitors the Windows Application log on computers running Exchange 2010 and generates this alert when the events specified in the following Details table are logged.

To learn more about this alert, in Operations Manager, do one or more of the following:

From the Operations Console, double-click this alert, and then click the General tab. Review the description of the alert that includes the variables specific to your environment.
From the Operations Console, double-click this alert, and then click the Alert Context tab. Review the logged events that meet the criteria of this Operations Manager alert.

Details

Product Name	Exchange
Product Version	14.0 (Exchange 2010)
Event ID	2120
Event Source	MSExchange ADAccess
Alert Type	Warning
Rule Path	Microsoft Exchange Server/Exchange 2010/Common Components/Active Directory Access
Rule Name	The DNS servers for the specified domain aren't responding.

Explanation

This Warning event indicates that DNS servers for the specified domain are not responding. The domain controllers from the specified domain will not be used by DSAccess. As long as there is sufficient capacity in usable domain controllers in other domains, it will not cause mail flow interruption. However, we recommend that you investigate the issue and fix it.

If the event contains the name of the local domain, topology discovery cannot be completed, and this will cause mail flow interruption.

This event may be logged when the following conditions occur:

The DNS servers did not respond because there is a connectivity problem.
There is no connectivity problem and the DNS servers are running. However, this computer could be using DHCP to obtain IP addresses for its DNS servers and the DHCP server could be providing incorrect IP addresses.

User Action

If this event is rarely seen, it can safely be ignored. To resolve this event, do one or more of the following:

If this Warning event is logged at specific times or if any other pattern is detected, do the following:
- Verify that the IP addresses of the DNS servers that are used by this computer are correct.
- Determine whether DNS servers are running. For more information about how to troubleshoot DNS issues, see DNS Troubleshooting.
- Determine whether this computer uses DHCP to obtain its DNS server IP addresses by typing ipconfig /all at the command prompt. Then, if the DHCP Enabled setting is set to Yes, this computer uses DHCP to obtain DNS server addresses. Contact the network administrator to verify that the DHCP server is running and providing correct DNS server IP addresses.
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.
Run the Dcdiag command-line tool to test 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 Windows Server TechCenter.

For More Information

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.