In a Network Load Balancing (NLB) cluster, port rules are configured to control how each port's cluster network traffic is handled. The NLB cluster may fail to converge unless each port rule has a unique host priority (a number between 1 and 32), the port rules are consistent on all cluster hosts, you are using the proper number of port rules, and the virtual IP address is specified in a valid IPv4 or IPv6 address format
Check uniqueness of host priorities in port rules
When single host filtering mode is used, traffic to the port or ports governed by that port rule is handled exclusively by the host whose priority has the lowest numeric value. When the host's single host priority is identical to the single host priority of another host, the cluster will not converge until the problem is corrected. You should check the NLB configuration of all port rules and make sure that each has a unique host priority (a number between 1 and 32).
To check that each port rule has a unique host priority:
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 Port Rules tab. In the Defined port rules list, review each port rule to make sure that each has a unique host identifier.
If there are port rules with identical host identifiers, right-click the host for which you want to reconfigure the host identifier, and then click Host Properties.
Click the Host Parameters tab, and in Priority (unique host identifier), specify a value between 1 and 32.