I'm testing with Firefox, and if I set a cookie domain to "example.com", I get ".example.com" anyway. If I set a cookie domain to null, Firefox does set it as "

I'm testing with Firefox, and if I set a cookie domain to "example.com", I get ".example.com" anyway. If I set a cookie domain to null, Firefox does set it as "example.com" and not ".example.com". Requests for a file from "static.example.com" do not include the cookie from "example.com".