A device’s IP address may change over time, but its MAC address is permanent. Address Resolution Protocol (**ARP**) is mainly a [[Network Access Layer]] protocol in the TCP/IP model used to *translate the IP addresses that are found in data packets into the MAC address* of the hardware device. Each device on the network performs ARP and keeps *track of matching IP and MAC addresses* in an *ARP cache*. ARP does not have a specific port number.