A feature of Hypertext Transfer Protocol (HTTP) version 1.1 supported by IIS that lets multiple Web sites hosted on an IIS 4 or IIS 5 Web server share the same IP address. Web browsers such as Microsoft Internet Explorer support host header names and can access these Web sites seamlessly.
To configure multiple virtual servers (Web sites) on an IIS server to share one IP address and use host header names for client access to them, perform the following steps:
Once the IIS server and DNS name resolution environment are configured properly, a Web browser that supports host header names, such as Internet Explorer 4 and later, can use these names to access different virtual servers that have the same IP address and port number and are located on the same machine running IIS. The browser makes an HTTP 1.1–compliant GET request, which contains in its header the host header name being requested.
Web browsers that support host header names include Internet Explorer 3 and later or Netscape Navigator 3 and later.
IIS 4 and later support host header names on older browsers by implementing a mechanism based on cookies. For very old browsers that don’t support cookies, a tool in the IIS Resource Kit called the Cookie Munger enables these browsers to access such sites on IIS 4.
Do not create host header names for the Default Web Site, because this might affect other services installed on the server that expect the Default Web Site to have no host header names.