Which statement is true about 802.1x port-based authentication?

A.
TACACS+ is the only supported authentication server type.

B.
If a host initiates the authentication process and does not receive a response, it assumes it is not authorized.

C.
RADIUS is the only supported authentication server type.

D.
Before transmitting data, an 802.1x host must determine the authorization state of the switch.

E.
Hosts are required to have a 802.1x authentication client or utilize PPPoE.

Explanation:

The IEEE 802.1x standard defines a port-based access control and authentication protocol that restricts unauthorized workstations from connecting to a LAN through publicly accessible switch ports. The authentication server authenticates each workstation that is connected to a switch port before making available any services offered by the switch or the LAN. Until the workstation is authenticated, 802.1x access control allows only Extensible Authentication Protocol over LAN (EAPOL) traffic through the port to which the workstation is connected. After authentication succeeds, normal traffic can pass through the port. Authentication server: Performs the actual authentication of the client. The authentication server validates the identity of the client and notifies the switch whether or not the client is authorized to access the LAN and switch services. Because the switch acts as the proxy, the authentication service is transparent to the client. The RADIUS security system with Extensible Authentication Protocol (EAP) extensions is the only supported authentication server.