802.1X authentication is a port-based network access control protocol, which verifies user identity and controls access rights at the port level of the access device. Which of the following…

Question

Options

• AClient associated device triggers authentication
• BThe associated device actively initiates
• CThe client sends a DHCP request message to trigger authentication.
• DThe client sends an EAPoL-Start message to trigger authentication

• A
  18% (7)
• B
  75% (30)
• C
  8% (3)

Explanation

802.1X defines exactly two triggering methods: the authenticator (access device) actively initiates by sending an EAP-Request/Identity frame when it detects a new connection (B), and the client initiates by sending an EAPoL-Start frame to signal it wants to authenticate (D). These are the two sides of the same handshake - either party can start it.

Option A is a distractor because it conflates the client with the associated device - in 802.1X terminology, the authenticating device (switch/AP) and the client are distinct roles; the client's mere act of associating does not itself trigger authentication without one of the two explicit mechanisms above. Option C is wrong because DHCP operates at Layer 3 and has no role in 802.1X, which is a Layer 2 (data-link) protocol - authentication must complete before a client can even receive an IP address, so DHCP cannot be the trigger.

Memory tip: Think "Both ends can knock" - the Box (network device) knocks with EAP-Request, or the client knocks with EAPoL-Start (Option D = Door opened by client). DHCP and vague "association" events are Layer 3/wireless concepts that don't belong in the 802.1X trigger picture.

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