I have a web application to which I want users to login only through their unique sub-domain (the sub-domain will be chosen at signup). So that I can scale the application across a number of servers, what would be the best way to set up Apache to always serve the same subdomains from the same server? For instance: matt.yyy.com, helen.yyy.com, terry.yyy.com are always served from server with ip of xxx.xxx.xxx.xxx suzi.yyy.com, fred.yyy.com, tom.yyy.com are always served from server with ip of xxx.xxx.xxx.xxx