DHCP snooping is a feature that exists on a switch. It creates two types of ports: trusted and untrusted. When DHCP snooping is enabled on a switch, all ports are labeled as untrusted, and this prevents any DHCP Offer and DHCP ACK messages from entering the switch. However, the port that is connected to the DHCP server should be configured manually as a trusted port. The trusted port allows the DHCP Offer and DHCP ACK messages to enter the switch.

The DHCP snooping feature is a countermeasure against any rogue DHCP server that may be attached to the network infrastructure.