What protocol is used to find the hardware address of a local device?

The protocol used to find the hardware address of a local device is ARP, which stands for Address Resolution Protocol. ARP works by mapping IP addresses to MAC (Media Access Control) addresses, allowing devices within a local area network to communicate effectively. When a device wants to communicate with another device on the same network and only knows the IP address, it sends out an ARP request. This request is broadcasted to all devices on the network, asking "Who has this IP address? Please send me your MAC address." The device with the matching IP address then replies with its MAC address, enabling the sender to encapsulate data in frames addressed to the correct hardware address for actual data transmission.

RARP (Reverse Address Resolution Protocol) is designed to do the opposite of ARP; it helps a device obtain its IP address based on its hardware address, making it less relevant in this context. IP (Internet Protocol) is primarily responsible for addressing and routing packets across networks, not for resolving hardware addresses. ICMP (Internet Control Message Protocol) is used for error messages and operational information but does not deal with hardware address resolution.