What is the purpose of ARP in an IPv4 network?

• A. To encrypt data on the local network.
• B. To determine the best path to a destination.
• C. To map IPv4 addresses to MAC addresses on the local network.
• D. To resolve domain names to IP addresses.

Answer: (D)

ARP maps IPv4 addresses to machine (MAC) addresses on the local network. This lets devices deliver frames to the correct hardware address because, on a LAN, data is addressed by MAC, not by IP. When a host needs to reach another device on the same local segment, it checks its ARP cache and, if it doesn’t know the MAC, it broadcasts an ARP request asking who owns that IP. The device with that IP replies with its MAC, and the sender stores this mapping for future use. This resolution is essential for local delivery and also applies to gateway devices when traffic must leave the local network. ARP does not encrypt data, does not pick the best path (that’s routing), and does not convert domain names to IPs (that’s DNS).