How can I use DNS to maintain different domain names on one server?
All DNS is designed for, is to map IP numbers to domain names. As far as DNS is concerned, you can map multiple domain names to the same IP number. It is up to the web server running on that IP number to distinguish requests for different domain names. This feature, often referred to as virtual hosting, is supported by most modern webservers. For example, if you’re running Apache, you can find documentation on how to do virtual hosting at this page (for Apache 2.0), or here (for Apache 1.3). A Microsoft Knowledge Base article on virtual hosting in IIS can be found here.