DAI (Dynamic ARP Inspection)

DAI blocks ARP spoofing by validating ARP packets against a trusted binding table.

Updated: 2026-03-05

Definition

Dynamic ARP Inspection (DAI) inspects ARP packets and drops those that do not match the DHCP snooping binding table.

It helps prevent man-in-the-middle attacks using ARP poisoning.

Key points

Prevents ARP spoofing
Uses DHCP snooping binding table
Trusted ports are typically uplinks

Common mistakes

Not enabling DHCP snooping first (no bindings).
Blocking legitimate ARP due to missing static bindings.

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