Microsoft Knowledge Base Article - 190008
How to: Using the host title name from an IP address multiple sites
http://support.microsoft.com/default.aspx?scid=kb;zh-cn; 190008&sd=tech
summary
This step-by-step guide describes how to use the host title to share multiple hostnames to share an IP address.
IIS allows you to assign any number of sites to a single IP address and use host titles to distinguish them. When IIS receives a request to a web page, it will view the information sent by the browser. If the browser complies with the HTTP 1.1 specification (Internet Explorer 3.x, or Netscape Navigator 3.x and later), the HTTP header contains the requested actual domain name. IIS Use this information to determine which site responds to this request.
If the browser is not the HTTP 1.1 specification, you can write a core page to display all available sites, let the user choose which site to use. For the operation instructions on this, see the final reference section of this article.
