What is the security feature that validates ARP packets in a network?

• A. DAI
• B. XArp
• C. MAC duplicating
• D. TMAC

Answer: (A)

Dynamic ARP Inspection is a security feature on switches that validates ARP packets. It uses a binding table built through DHCP snooping to know the legitimate IP-to-MAC mappings and the port they should be associated with. When an ARP packet arrives, the switch checks the claimed IP and MAC against this binding. If there’s a mismatch or no binding, the ARP packet is dropped, stopping ARP spoofing and man-in-the-middle attempts. This is why it’s the best choice: it provides automatic, on-network-layer verification of ARP traffic and relies on DHCP snooping to maintain trusted mappings.

Other options aren’t standard ARP-validation mechanisms on network gear: XArp is a separate detection tool, MAC duplicating isn’t a formal security feature for ARP validation, and TMAC isn’t a recognized method for securing ARP in typical enterprise networks.