Any number of domain names can resolve to one IP address. That isn't a problem in and of itself. When a web server gets an HTTP request, the domain name requested by the client is included in the headers. That's how the web server works out which set of pages to use. NINJAM isn't anything to do with web servers or HTTP, though. First, you need your ISP to have the port you're running NINJAM on open for incoming connections. Then that port needs forwarding to the physical machine you're running NINJAM on. If you've had the ISP set that up for you, you should be OK. (At home, all our machines are hidden behind the ADSL router's IP address. I need to configure the router to forward incoming connections to the right machine. It's similar to what you're after, I would imagine.)