Which protocol is used for direct communication between two devices within the same LAN segment?

The Address Resolution Protocol (ARP) is specifically designed for direct communication between two devices on the same Local Area Network (LAN) segment. ARP helps map a device's Internet Protocol (IP) address to its corresponding physical MAC (Media Access Control) address on that local network.

When a device wants to communicate with another device on the same LAN, it first needs to know the MAC address associated with the IP address it is trying to reach. It sends out an ARP request in a broadcast manner, asking "Who has this IP address?" The device that owns that IP address responds with its MAC address in an ARP reply. This process allows devices to discover each other's MAC addresses and establish a direct communication channel, enabling efficient data transmission within the LAN.

In contrast, the other protocols listed serve different purposes: Internet Protocol (IP) is responsible for routing packets across networks; Transmission Control Protocol (TCP) provides reliable communication over IP networks; and Dynamic Host Configuration Protocol (DHCP) is used for assigning IP addresses and network configuration parameters dynamically to devices on a network, not for direct device-to-device communication within a LAN segment.