url redirect with rewrite capability

Now you have totally lost me. :)

You want http://bearcub.dev.leo.world.com/lookout to show the content of http://lion.dev.leo.world.com/lookout, but you don't want the browser location bar to change. Am I right?

But now you say that you don't want to fetch any content from the site bearcub.dev.leo.world.com?

In order to prevent the location from changing you need to rewrite the request in the load balancers to match another site on the server side. The only other options would be to do a redirect (which always changes the browser location bar), or actually host the content you want on the server.

Please note that replacing the hosts header is not the same as changing the location bar in the browser. The hosts header is a header that's basically only used by the server, ie for choosing which site the request should go to. When changing the hosts header for incoming requests the client would never notice the change, except for the fact that they would get different content.

Check out this article for a better explanation:

http://www.it-notebook.org/iis/article/understanding_host_headers.htm

/Patrik