Which statement is true about 802.1X closed mode?
A.
Only EAPOL and Cisco Discovery Protocol are allowed until the authentication process
completes.
B.
It is the default configuration of an 802.1X-enabled switch port.
C.
Only EAPOL traffic is allowed until the authentication process is finished.
D.
DNS and DHCP are allowed before authentication.
E.
Cisco Discovery Protocol is allowed before authentication.
Until the client is authenticated, 802.1x access control allows only Extensible Authentication Protocol over LAN (EAPOL), Cisco Discovery Protocol (CDP), and Spanning Tree Protocol (STP) traffic through the port to which the client is connected. After authentication is successful, normal traffic can pass through the port.
http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/12-2_55_se/configuration/guide/3750xscg/sw8021x.html