Hosts in a Network Load Balancing (NLB) cluster are configured to load balance network traffic. Host configuration is set by using NLB Manager, and if it is not configured properly, the NLB cluster may not function correctly.
Check that the virtual network mask is valid
The virtual subnet mask must be in the standard format.
To check that the virtual subnet mask is correctly specified:
Click Start, click Administrative Tools, and then click Network Load Balancing Manager. You can also open NLB Manager by typing Nlbmgr at a command prompt.
If NLB Manager does not already list the cluster, connect to the cluster.
Right-click the cluster, and then click Cluster Properties.
Click the Cluster Parameters tab, and, in Subnet mask, verify that the subnet mask is correctly specified. The mask should be entered in standard Internet dotted notation (for example, 255.255.255.0).