ASP.NET MVC：如何在所有设备上实现注销

Question

我有两行，一行是：https://stackoverflow.com/a/27288275/728750

以上链接说：

It is possible , Facebook, Gmail have done that , But it is not simple.

Use a flag in the database that checks users on Session_Start that invalidates their session 
If that flag is set. May not necessarily use a Boolean, you can use a DateTime value and 
invalidate all sessions that started prior to that time. This could be done by checking a value stored in a cookie upon login.

What they trying to say is not clear.

How to implement this "you can use a DateTime value and invalidate all sessions that started prior to that time."?

  

如何知道用户会话何时开始？

我有另一个好的链接：https://stackoverflow.com/a/5492396/728750

这条线不清楚：

authCookie.Expires < logoutTime.Value

上述行如何运作？假设我现在登录网站，今天日期是01/01/16，登录过期日期是07/01/16，我强制退出于02/01/16那么这个到期日期07/01/16将如何小于强制注销日期02/01/16。目前尚不清楚。任何人都可以帮我实现这个吗？感谢。