The network adapter to which Network Load Balancing (NLB) is bound must be properly configured and capable of performing NLB operations. If the adapter is not properly configured, the NLB driver may fail to bind to the adapter.
Change network adapter or operate NLB in multicast mode
To operate in unicast mode, Network Load Balancing (NLB) must alter the unicast MAC address on the network adapter that it will be using. A problem occurs when the network adapter to which NLB is trying to bind does not support the dynamic changing of its unicast MAC address. To resolve this, you can either replace the network adapter with one that supports changing the unicast MAC address dynamically or operate the NLB cluster in multicast mode.
To change the cluster operation mode to multicast:
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 specify Multicast in Cluster Operation Mode.