The Cluster Does Not Start After You Change the Subnet Mask of the Network Adapter

After you change the subnet mask of the network adapter that connects to the public network on a cluster node, the Cluster service may not start, or IP address resources may not go to an Online state.

This behavior occurs because the subnet mask of all the IP address resources remain set to the original subnet mask when you change the subnet mask of the cluster node. This causes the IP address resources to enter a Failed state. Resources that depend on the IP address resources enter an Offline state. Additionally, the Cluster Administrator tool may not start because the Network Name resource is in an Offline state.

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk. To resolve this issue, verify the Subnet Mask value of all the IP address resources. To do so, follow these steps:Note Because there are several versions of Microsoft Windows, the following steps may be different on your computer. If they are, see your product documentation to complete these steps.

1. Start the Cluster Administrator utility. If you are not prompted to open a connection to a cluster, click Open Connection on the File menu.
2. In the Cluster or server name box, type:
   . (a period)
3. Click Open.
   
   Note This causes the Cluster Administrator tool to connect to the local Cluster service instead of going through the network to connect.
4. For all the IP address resources that are on the network where you have changed the subnet mask, make sure that the subnet mask is correct. To do so, follow these steps:
   1. Under the cluster node that owns the IP address resource, click Active Resources.
   2. In the right pane, double-click the IP address resource, and then click the Parameters tab.
   3. Type the correct subnet mask in the Subnet mask box, click OK, and then click Yes if you are prompted to verify the subnet mask.
   For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
   327150 Cluster Resource Appears to Stop Responding in an Online Pending State or an Offline Pending State
5. In the Cluster Administrator tool, view the properties of the network where you have changed the subnet mask to make sure that the subnet has been updated. The Cluster service uses Plug-and-Play to update its network settings each time the node network configuration changes. If the Subnet Mask list contains the original subnet mask, manually remove the original subnet mask to fix it. This is only a display problem. If the nodes are on the same subnet as the IP address resources, the IP addresses come online and function correctly. The Cluster Administrator tool is displaying the incorrect subnet mask. To resolve the issue, follow these steps:
   
   Note You must take the whole server cluster offline before you follow these steps.
   1. Back up the server cluster.
   2. Shut down all the cluster nodes except one.
   3. Stop the Cluster service on the remaining cluster node.
   4. Start Registry Editor.
   5. Locate the following registry subkey:
      HKEY_LOCAL_MACHINE\ Cluster\NetworkInterfaces
   6. On the Registry menu, click Export Registry File.
   7. In the File name box, type:
      exported networkinterfaces
   8. Click Save.
      
      Note If you want to restore this registry key later, double-click the exported networkinterfaces.reg file that you saved.
   9. Under NetworkInterfaces, delete the GUID registry keys whose Name value corresponds to the name of the network adapters on the nodes where you changed the subnet mask.
   10. Locate the following registry subkey:
       HKEY_LOCAL_MACHINE\Cluster\Networks
   11. On the Registry menu, click Export Registry File.
   12. In the File name box, type:
       exported networks
   13. Click Save.
       
       Note If you want to restore this registry key later, double-click the exported networks.reg file that you saved.
   14. Under Networks, delete the GUID of the networks that correspond to the network interfaces you previously deleted. The AddressMask value appears as the original subnet mask.
       
       Note You must delete the GUID registry key. You cannot delete or update only the AddressMask value.
   15. Quit Registry Editor, and then start the Cluster service.
   16. Verify that the Subnet Mask value is updated for the network in the Cluster Administrator tool. For additional information about how to configure the network settings in a server cluster, click the following article number to view the article in the Microsoft Knowledge Base:
       258750 Recommended Private "Heartbeat" Configuration on a Cluster Server
   17. Start the other cluster nodes.