As Nitass suggests, you could still transparently proxy requests to the second site even if it's not directly on an LTM subnet. LTM would need to have a route to the site. You'd want to rewrite the host header on requests as Naladar has shown and select a pool with the server(s) for the second site configured. If you need to dynamically look up the IP address(es) for the second site, you could do this with an iRule which calls RESOLV::lookup (http://devcentral.f5.com/wiki/default.aspx/iRules/resolv__lookup). You'd probably need to SNAT the serverside connection as well.
Hi Aaron, actually second website is not in our domain, it is a public website like google.com, is it still possible to rewrite public url with our own url. In other words, users are seeing our url and they are actually accessing some public blogsite. Thanks
As long as LTM has a route to the IP address(es), it doesn't matter who "owns" the server. You can transparently proxy traffic to the site. See my post above for details on how to do this. If you try an iRule and get stuck let us know.