ASP.NET Request.Cookies["ASP.NET_SessionId"] vs SessionId

1. What is the difference between:

   HttpContext.Current.Request.Cookies["ASP.NET开发者_StackOverflow_SessionId"].Value

and

System.Web.SessionState.HttpSessionState.SessionId

(while debugging, both of the values were always the same)

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Well there exists more than one method of how ASP.NET handles a session. It's configurable by the web.config for example.

One of them is by cookies. Another one is by putting the session ID inside of the url. I boldly presume you won't be able to find the session ID in the cookie collection in that second case.

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ASP.Net uses that cookie to track the session across requests. They will always be the same value. For more details: http://msdn.microsoft.com/en-us/library/ms178581.aspx