CompTIA A+ 220-802

Answer: C - You would use a Loopback Plug to verify that a NIC installed in your computer has a faulty Ethernet port.

Key Takeaway: A Loopback plug allows you to test the connectivity of a port by plugging the device in and seeing if data creates a loop. If it does (or does not) a light indicating so appears on the device. A cable tester verifies data can be transferred on a cable, a crimper is used to make a physical cable, and a multimeter is used to gather certain electrical information about a circuit.