Which protocol is used to map IP addresses to hardware addresses on a local network?

• A. DNS
• B. ARP
• C. DHCP
• D. NAT

Answer: (B)

ARP, the Address Resolution Protocol, is used to map IP addresses to hardware (MAC) addresses on a local network. When a device needs to send a frame to another device on the same LAN, it first checks its ARP cache for the MAC corresponding to the destination IP. If the MAC isn’t known, it broadcasts an ARP request asking who has that IP, and the device that owns the IP replies with its MAC address. The requester then caches this mapping and uses the MAC to deliver the frame at Layer 2. This process happens only within the local network and is specific to IPv4 (with IPv6 using a similar Neighbor Discovery approach). DNS maps domain names to IP addresses, not MAC addresses; DHCP assigns IP configuration to hosts; NAT translates addresses between private and public networks.