我只是不知道在两个不同的域之间共享 cookie 是否可行,但是当我需要在两个子域之间共享 cookie 时,我会按照以下方式进行
HttpCookie cookie = new HttpCookie("cookiename", "value");
cookie.Domain = "domain.com";
For forms authentication set this in web.config
<forms name=".ASPXAUTH"
loginUrl="login.aspx"
protection="All"
timeout="30"
path="/"
requireSSL="false"
domain="domain.com">
</forms>