What is ARP and what problem does it solve?

• A. Address Resolution Protocol maps a MAC address to an IP address on the local network for frame delivery.
• B. Address Resolution Protocol maps an IP address to a MAC address on the local network for frame delivery.
• C. Automatic Resource Provisioning protocol allocates network resources.
• D. Address Resolution Protocol routes traffic between networks.

Answer: (B)

ARP translates an IP address to a MAC address on the local network so frames can be delivered. On Ethernet, devices move data using MAC addresses, but higher-layer communication uses IP addresses. When a host knows the destination IP but not its MAC, it broadcasts an ARP request asking who has that IP. The device with that IP replies with its MAC, and the requester caches this mapping for faster use next time. This enables correct local delivery of frames without routing. ARP operates only on the local link; routers handle traffic between networks. For IPv6, a different mechanism (Neighbor Discovery) takes over address resolution.