ARP

Address Resolution Protocol

Is used to discover the Layer 2 address (MAC address) of a known Layer 3 address (IP address).

Consists of two messages:

• ARP Request

  • Is broadcast. Destination MAC: FFFF.FFFF.FFFF

• ARP Reply

  • Is unicast.

ARP Table

Use arp -a to view the ARP table.

Correlates an IP address with a MAC address (Physical Address).

Static

Is a default entry.

Dynamic

Learned via ARP.