Wanting to write rule to append fully qualified URL

I am trying to write a rule that basically says if anyone types in the server name, they will get forwarded to the fully qualified URL on that server. For Example:

User goes to http://esupport

URL rewrite redirects to 

http://esupport.domain.com/site1

All example ruiles talk about is after tha fact of the HTTP_HOST. I want them to all be transferred to the FQ URL. Has anyone done this?

Thanks in advance.