A technician is working on a desktop PC and wants to verify its NIC is...

A loopback plug is a device that can be used to test the functionality of a network interface card (NIC) by sending and receiving data packets from itself. The loopback plug connects to the NIC’s port and simulates a network connection without requiring another device or cable. The technician can use a loopback plug to verify that the NIC is able to transmit and receive data without errors or interruptions.