The scenario like following
We have a web site which is www.testweb.us, also we have login.testweb.us for user login.We used www.testweb.us/cms/to/ui/cms to login CMS admin.
The problem is when we login www.testweb.us, the login user cookie(.ASPXAUTH) domian is .testweb.usIn same time and same browser we login www.testweb.us/cms/to/ui/cms, it will have same name cookie(.ASPXAUTH) and domian is www.testweb.us Because .testweb.us is root domian, two cookies with same name will cause authentication confusion (1. Website .ASPXAUTH domain:.testweb.us 2.CMS admin .ASPXAUTH domain:www.testweb.us ), one of them will not work when login to both, the first cookie will be used for both.
You can change the name of the cookie in the forms authentication section of web.config, see: http://stackoverflow.com/questions/6661943/can-i-change-the-formsauthentication-cookie-name
You can also explicitly set the domain the cookie, see: https://msdn.microsoft.com/en-us/library/system.web.security.formsauthentication.cookiedomain%28v=vs.110%29.aspx
Thanks for your feedback. But My scenario is not only change the cookie name. I use another way to sloved this.