Since the web server can not read minds, it has to use something to tell requests apart between applications/sites. You have three choices:
1) different ports and one IP
2) different IP
3) using CNAME aliases
Here is the howto for IIS6 for all three cases, look at the menu on the left: http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/55161df5-5f55-4ed3-bb26-b675153d49ac.mspx?mfr=true
This later option is used by the service providers to do simple web hosting. The browser sends out a Host header
] in the http request. This is used by IIS to distinguish between targets on the same web server. Simple and easy. All you have to do is add a CNAME alias with a friendly name to DNS at the level you need (in your case this will be most likely the company DNS server).
Let's suppose, your machine is
, and you have
, than you should register two CNAME records
] in the DNS:
, both pointing to the original server name. Than you can assign these aliases to your sites. That's all.