Windows NLB load balancing is free to use with Windows Server.
If 2 servers are setup in cluster: Server 1 and Server 2
- There is a Virtual IP address (VIP) bound to 2 network cards (NICS), the main site domain is setup to point at this.
- All requests use sticky sessions
- Server 1 is the primary server and all routing is directed via server 1
If Server 1 fails
- any new connections are refused
- existing users on Server 2 are ok
If Server 1 is gracefully removed from cluster
- Server 2 becomes primary
- Existing users on Server 1 will lose session and be redirected to Server 2
If Server 2 fails or is gracefully removed from cluster
- All requests are handled by Server 1
- Existing users on Server 2 will lose session and be redirected to Server 1
If Server 1 fails server 2 can be made the primary server manually.