What is the protocol that is used to discover a physical address from a known logical address and what message type does it use?

The protocol used to discover a physical address from a known logical address is the Address Resolution Protocol (ARP). ARP operates by broadcasting an ARP request message on the local network, which contains the known logical address (IP address) and asks for the corresponding physical address (MAC address). The device that owns the requested IP address responds with an ARP reply message, providing its physical address. This process enables devices on the same local network to communicate effectively.