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The Address Resolution Protocol (ARP) is used to discover the Media Access Control (MAC) address associated with a given IP address within a local network. When a device wants to communicate with another device on the same network and only knows the target device's IP address, it sends out an ARP request. This request essentially asks, "Who has this IP address? Please send back your MAC address." Devices on the network that recognize the IP address will respond with their MAC address. This mechanism is crucial for enabling communication over Ethernet and similar networks, as it allows devices to obtain the necessary link-layer information to forward packets appropriately at the data link layer.

The other protocols do not serve this purpose; IP (Internet Protocol) is responsible for logical addressing and routing packets across networks, TCP (Transmission Control Protocol) is used for establishing connections and ensuring reliable data transfer, and ICMP (Internet Control Message Protocol) is used primarily for error messages and operational queries. Therefore, ARP stands out as the protocol specifically designed for mapping IP addresses to MAC addresses in a local network environment.