What function does the ARP protocol serve?

The ARP (Address Resolution Protocol) serves the critical function of resolving IP addresses to MAC (Media Access Control) addresses. In a network, when a device wants to communicate with another device using its IP address, it first needs to find out the corresponding MAC address, which is necessary for the data to be sent over the local network segment.

When a sender has only the IP address of the recipient, it broadcasts an ARP request on the local network, asking, "Who has this IP address?" The device that owns the IP address responds with its MAC address. This resolution is essential because while communication on IP relies on logical addressing, actual data transmission at the data link layer (Layer 2) relies on physical addressing provided by MAC addresses. This process enables devices to successfully locate and communicate with each other on the same local network.

The other options do not accurately describe the function of ARP. For example, encryption of data is handled by different protocols, DHCP (Dynamic Host Configuration Protocol) is responsible for assigning IP addresses to devices on a network, and the task of replicating network traffic typically involves specific networking devices or protocols for monitoring or load balancing, not ARP.