It's simply how cookies work.
Cookies aren't valid for more than one domain as Alex pointed out.
Cookies have a -domain parameter that sets the valid domain for the cookie, hence it can only be valid for one domain.
You can set a cookie over different sub-domains though.
Cookies aren't valid for more than one domain as Alex pointed out.
Cookies have a -domain parameter that sets the valid domain for the cookie, hence it can only be valid for one domain.
You can set a cookie over different sub-domains though.