Windows Load Balancing Service (WLBS) provides scalability and high availability to enterprise-wide TCP/IP services, such as Web, Proxy, Virtual Private Networking, and streaming media services. WLBS allows incoming IP traffic to be dynamically distributed across cluster nodes (up to 32 nodes). WLBS can automatically detect whether a node in the cluster fails. When this occurs, the remaining nodes can adjust to take over the workload.

Microsoft Cluster Service (MSCS) is software that supports the connection of two servers into a cluster for higher availability and easier manageability of data and programs such as Microsoft SQL Server, Microsoft Exchange Server, and so on. MSCS can automatically detect and recover from server failures or program problems.

WLBS is fully complementary to MSCS. MSCS provides a reliable platform for database, messaging, and related program services by using "failover" for two nodes, while WLBS balances and distributes client connections (TCP/IP connections) over multiple servers. In a two-tier configuration, MSCS handles the back-end data service layer, while WLBS handles the front-end client user interface (UI) layer.

Currently, Microsoft does not recommend or support running MSCS and WLBS on the same node. The effect of the failover of MSCS on WLBS' handling of the virtual IP address on the cluster network adapter has not been tested.

MSCS' IP addresses should not be the same as WLBS' virtual IP address. MSCS could use WLBS' dedicated IP address or another IP address on a different network adapter.