Which protocol is used to learn the MAC address corresponding to an IP address?

• A. ARP
• B. DNS
• C. DHCP
• D. ICMP

Answer: (A)

Learning the MAC address that belongs to a known IP address happens through ARP. On IPv4 networks, devices need the destination’s MAC to place frames on the local network, while they operate with IP addresses at the routing layer. ARP bridges this gap by asking, on the local broadcast domain, “Who has this IP address? Tell me your MAC address.” The device that owns that IP responds with its MAC address, and the requester caches this mapping for future packets. This is why ARP is the protocol used for learning the MAC address from an IP address; it’s the mechanism that translates IP to the corresponding hardware address on the local network.

DNS, on the other hand, translates domain names to IP addresses, not MACs. DHCP assigns IP configuration to hosts and uses the MAC as an identifier during lease management, but it doesn’t map an IP back to a MAC. ICMP is for diagnostic and control messages (like echo requests/replies and error messages), not for address resolution.