Which protocol is responsible for resolving IP addresses into MAC addresses?

The protocol responsible for resolving IP addresses into MAC addresses is ARP, which stands for Address Resolution Protocol. ARP operates at the network layer of the OSI model and is essential for enabling communication on local networks. When a device wants to communicate with another device within a local area network (LAN) using its IP address, it needs to know the corresponding MAC address for that IP address.

To achieve this, the sending device broadcasts an ARP request packet over the network, asking which device has the specific IP address. The device that owns that IP address responds with its MAC address in an ARP reply. This process allows the sending device to encapsulate its data in a frame containing the correct MAC address, enabling effective communication over the physical network.

In the context of networking protocols, other options serve different purposes. DHCP (Dynamic Host Configuration Protocol) is used for dynamically assigning IP addresses to devices on a network. DNS (Domain Name System) translates human-readable domain names into IP addresses, facilitating easier access to resources on the internet. STP (Spanning Tree Protocol) is a network protocol that ensures a loop-free topology in Ethernet networks but does not deal with IP to MAC address resolution.