Cookies over multiple sub domains except one

So I know you can share your cookies across subdomains eg. staging.mysite.com and www.mysite.com etc by setting the domain of the cookies to ".mysite.com"

BUT, is there a way to share across all the sub dom开发者_如何转开发ains EXCEPT one. e.g. the cookies will not persist on images.mysite.com?

As far as I know this is not possible and that's why sites like stackoverflow use a cookieless domain for static resources which is different than the main domain: http://sstatic.net

That's also part of the recommendations of YSlow for optimizing web applications.