A Windows Server failover cluster requires a distinct IP address for each individual cluster node ' s network adapter, plus one additional IP address for the cluster ' s own network name resource -- the cluster access point that clients and management tools use to address the cluster as a single logical entity rather than any one specific node. Cluster3 will contain two physical nodes, Node1 and Node2, so at minimum one IP address is required for Node1 ' s network adapter and one for Node2 ' s network adapter. Beyond those two node-level addresses, the cluster core resource itself (the cluster name object and its associated IP address resource) requires one more address so that the cluster can be addressed and managed as a whole and so that any highly available roles hosted on the cluster (such as the file share role planned for Cluster3) can obtain the network identity they need to fail over between nodes. Adding these together -- one for Node1, one for Node2, and one for the cluster ' s own network name -- yields a minimum of three IP addresses required for Cluster3 ' s node and cluster roles. Fewer than three would leave either a node or the cluster itself without a usable network identity, and while additional IP addresses may be consumed by highly available roles later added to the cluster, three is the baseline minimum for the node and cluster roles themselves.