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DHCP snooping binding table

As explained in Acing the CCNA Exam: Volume 2 Advanced Networking and Security

A DHCP snooping binding table is a switch-maintained table mapping leased IP addresses to client MAC addresses, VLANs, interfaces, and lease information.

A DHCP snooping binding table records clients that successfully leased addresses through DHCP. Each entry maps an IP address to a MAC address, VLAN, interface, and remaining lease time. section 14.2 section 13.2.1

The switch builds and uses the table as DHCP exchanges pass through its ports:

  • Creates an entry after a client successfully leases an IP address. section 13.3
  • Stores the client MAC address, leased IP address, lease duration, entry type, VLAN, and receiving interface. section 13.2.1
  • Verifies RELEASE and DECLINE messages by matching their IP address and receiving port against the binding. section 13.3
  • Supplies host-to-address information to Dynamic ARP Inspection, which uses matching bindings when filtering ARP messages. section 14.2 section 14.2.1

Verify the table

Use show ip dhcp snooping binding. For example, an entry can show MAC address 52:54:00:08:D3:E0, IP address 10.0.0.6, 84,617 seconds remaining, type dhcp-snooping, VLAN 1, and interface Gi0/2. The command also reports the total number of bindings.

How Acing the CCNA Exam: Volume 2 Advanced Networking and Security covers it

How deep it goes
Explains entry creation, stored fields, message validation, and verification output, but does not detail table storage internals.
Examples
Shows Cisco IOS output containing MAC addresses, IP addresses, lease timers, VLANs, interfaces, and a binding count.
What it assumes
Assumes familiarity with DHCP client and server messages, leased IP addresses, MAC addresses, VLANs, and switch interfaces.
What you can do after
Diagnose binding state with show ip dhcp snooping binding and interpret client-to-address mappings used by security checks.
How it connects
Connects DHCP snooping with DHCP, trusted and untrusted ports, Dynamic ARP Inspection, and ARP poisoning protection.
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of Acing the CCNA Exam: Volume 2 Advanced Networking and Security. The section links point to the parts of the book it draws on.