Quick Definition
A switch security feature that filters DHCP messages to prevent rogue DHCP servers.
DHCP Snooping filters DHCP traffic to prevent rogue DHCP servers from assigning incorrect IP addresses to clients. Switch ports are classified as trusted (connected to legitimate DHCP servers) or untrusted (connected to clients). DHCP server responses (OFFER, ACK) are only forwarded from trusted ports — responses from untrusted ports are dropped. DHCP Snooping also builds a binding table mapping MAC addresses, IP addresses, ports, and VLANs, used by Dynamic ARP Inspection (DAI).
ip dhcp snooping ip dhcp snooping vlan 10,20 interface GigabitEthernet0/1 ip dhcp snooping trust ! uplink to real DHCP server
DHCP Snooping must be enabled globally and per VLAN. Ports facing DHCP servers must be explicitly trusted; all other ports are untrusted by default. Without trust, legitimate DHCP server responses are dropped.
A protocol that automatically assigns IP addresses and network parameters to clients.
A switch feature that limits the number of MAC addresses allowed on a port.
A switch security feature that validates ARP packets using the DHCP Snooping binding table to prevent ARP spoofing.
DHCP Snooping filters DHCP traffic to prevent rogue DHCP servers from assigning incorrect IP addresses to clients. Switch ports are classified as trusted (connected to legitimate DHCP servers) or untrusted (connected to clients). DHCP server responses (OFFER, ACK) are only forwarded from trusted ports — responses from untrusted ports are dropped. DHCP Snooping also builds a binding table mapping MAC addresses, IP addresses, ports, and VLANs, used by Dynamic ARP Inspection (DAI).
DHCP Snooping must be enabled globally and per VLAN. Ports facing DHCP servers must be explicitly trusted; all other ports are untrusted by default. Without trust, legitimate DHCP server responses are dropped.
DHCP Snooping falls under the Security domain of the 200-301 exam. Understanding it in context with related terms like dhcp and dynamic-arp-inspection is essential for answering scenario-based questions correctly.