How is this code used in the main site?
in reply to Load balancer
When you run it, it becomes your main web server for handling all web requests instead of Apache or something else you use. Make sure none of those other servers are already running and listening on port 80. You will have to edit @HOSTS variable and fill in your hostnames. It doesn't work out of the box.
but what should I see to know it works as advertised?
I would run it and try it and see for myself. It might be enough for your situation, or you will have to install something more robust.