The load balancer distributes the workload among multiple instances , increasing the overall throughput of the system. This section includes information on configuring the load balancer plug-in that is included. The plug-in works with the Sun Java System Web Server, as well as the Apache Web Server and Microsoft IIS. Hardware load balancers are also available. The load balancer also enables requests to fail over from one server instance to another. For HTTP session information to persist, configure HTTP session persistence. For more information about how a load balancer is set up and used, see the following topics: