Windows Network Load Balancing comes built-in with Windows Server 2008 R2, 2012, and 2012 R2. This allows two or more Windows servers to participate in a load balanced cluster. This cluster requires heartbeating between nodes to check for uptime and connectivity. The NLB works by sharing a virtual IP between hosts; this requires changing or spoofing the MAC address for the cluster IP. All hosts must have static IPs.
Windows Network Load Balancing offers the following advantages:
Windows load balancing is supported and included in Windows 2008 R2, 2012, and 2012 R2, which means that the Security and Connection servers should already be licensed to use it.
It supports up to 32 servers in a load balanced cluster.
Servers can be added or removed on the fly. Note that clients connected to a removed server will get disconnected.
Server failures are detected and traffic is rerouted.
Load can be distributed via weighted average.