Dynamic ARP Inspection (DAI) is a security feature that protects ARP (Address Resolution Protocol) from an attack like ARP poisoning. ARP poisoning is a technique where an attacker sends forged ARP responses to trick hosts into associating IP addresses with the attacker’s MAC address. This allows the attacker to intercept, modify, or drop traffic between the victims, creating a “man-in-the-middle” scenario. DAI can prevent this attack by validating ARP packets on untrusted interfaces, using information from the DHCP snooping database and/or an ARP access-list. If the ARP packet contains invalid MAC address to IP address bindings, it will be dropped and logged. DAI can also rate-limit ARP packets to mitigate ARP flooding attacks. DAI is configured on a per-VLAN basis and requires DHCP snooping to be enabled on the same VLANs. References :=

Some possible references are:

Implementing and Operating Cisco Security Core Technologies (SCOR) v1.0, Module 2: Network Security, Lesson 2.4: Implement Layer 2 Security

Understanding and Configuring Dynamic ARP Inspection

DAI (Dynamic ARP Inspection)