Cookies/Session Management

Well, you can work around this issue by making your website work on and all other subdomains to redirect to your website.

If you tell rails to use * for your cookie (dunno how to do that), you are going to have problems if you decide to use a subdomain for something else, like a forum, that usually sets a cookie on its own.

As it is, this is indeed an issue with you/app and not the web host.