802.1X authentication process in Active Directory joined computer.

Question

Hi,
I'm not really sure my understanding of the authentication process of an Active Directory joined computer, and I would like to know the purpose of multiple times auth as described below:
1. When Windows start up,
2. it will authenticate to the 802.1x network using computer account.
3. When user entering AD credential and pressing login, it will disconnect the current 802.1x connection. Re-auth to the network through AD user account.
4. once 3 is done, the AD credential will be used to auth to AD again to login.
Why do we need 3 times of authentication? Why do we need steps 3?
Note: this is just my current understanding on one of the mode of 802.1x authentication. Please feel free to correct and add more information so that I can understand 802.1x authentication more precisely.
Thank you!
Ah_Chao|| MCSE,VCP,EMCSAe

Answer 1

Hi,
According to your description, my understanding is that you want to know the reason why 802.1x has 3 times authentication.
It is depends on your 802.1x settings. The option Computer Authentication (allows you to specify how computer authentication works with user authentication). One of the possible settings is
With User Re-Authentication. When users are not logged on to the computer, authentication is performed using the computer credentials. After a user logs on to the computer, authentication is performed using the user credentials. When a user
logs off of the computer, authentication is performed with the computer credentials. This is the recommended setting because it ensures that the connection to the wireless AP is always using the security credentials of the computer's current security context
(computer credentials when no user is logged on and user credentials when a user is logged on).
Detailed description you may reference:
https://technet.microsoft.com/en-us/library/cc755892%28WS.10%29.aspx?f=255&MSPPError=-2147217396
And more information about 802.1x, you may reference:
Understanding 802.1X authentication for wireless networks
https://technet.microsoft.com/en-us/library/cc759077(v=ws.10).aspx
IEEE 802.1X Wired Authentication
https://technet.microsoft.com/en-us/magazine/2008.02.cableguy.aspx
Creating a secure 802.1x wireless infrastructure using Microsoft Windows
http://blogs.technet.com/b/networking/archive/2012/05/30/creating-a-secure-802-1x-wireless-infrastructure-using-microsoft-windows.aspx
Best Regards,
Eve Wang
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