Use another domain for a part of url

[eluser]TheFuzzy0ne[/eluser]
Yes and no.

Cookies set by one second-level domain can't be read by another. Can you imagine how unsecure that would be?

Since server's don't have direct access to your hard drive, your browser has to send the right cookies for the domain that's handling the request. So a cookie set by example.com would not be readable by foobar.com.

It is possible to emulate cross-domain cookies, but your apps would need to communicate with one-another (and securely) in order to share cookie data. I've never needed to implement anything like that before, so I'm not really sure how I'd go about carrying out the process.