asp.net中Cookie跨域问题

以下是创建一个跨域的Cookie,只能实现同一个根域下的Cookie
如：www.126.com，在这个根域下的所有二级域名可共享Cookie,{mail.126.com,photo.126.com}
        public static bool CreateCookie(string strCookieName, string strCookieValue, string strDomain, bool blURLEncode)
        {
            if (blURLEncode)
            {
                strCookieValue = System.Web.HttpContext.Current.Server.UrlEncode(strCookieValue);
            }
            HttpCookie objCookie = new HttpCookie(strCookieName, strCookieValue);
            objCookie.Domain = strDomain; //设置Cookie的域名
            System.Web.HttpContext.Current.Response.Cookies.Add(objCookie);
            return true;
        }