What is the primary function of ARP (Address Resolution Protocol)?

The primary function of ARP (Address Resolution Protocol) is to map MAC addresses to IP addresses. When a device on a local area network needs to communicate with another device, it must know the MAC address associated with the target device's IP address. ARP enables this by sending out a broadcast message on the local network asking, "Who has this IP address? Please send me your MAC address." The device that owns the IP address responds with its MAC address, allowing the requesting device to proceed with the communication. This mapping is essential for the functioning of network communications that involve different layers of the OSI model.

The other options describe functions that are not part of ARP's role. For instance, resolving IP addresses without broadcasting does not accurately capture ARP's functionality, as ARP is inherently a broadcast protocol used to discover MAC addresses. Translating domain names to IP addresses is a function of the Domain Name System (DNS), separate from ARP. Lastly, routing packets through the internet pertains more to routing protocols and functionality that operates at higher layers, not directly related to the address resolution that ARP provides.