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220-1201 Practice Question: A small office uses a network switch with 24 RJ45…
A small office uses a network switch with 24 RJ45 ports to connect all workstations. The switch is connected to the router via a single uplink port. Users report intermittent network drops. The technician suspects a faulty cable between the switch and router. Which tool should be used to test the cable?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Cable tester
A cable tester verifies continuity, wiring, and signal integrity in Ethernet cables. This is the correct tool to diagnose a faulty physical connection between the switch and router.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Tone generator and probe
Why it's wrong here
A tone generator and probe is primarily used for physically locating and identifying specific cables within a bundle or wall, by injecting an audible signal onto a wire and tracing it with the probe. While useful for mapping infrastructure, it does not assess the electrical integrity of the cable, such as shorts, opens, or correct pinout, which are crucial for network performance. This tool helps identify which cable goes to which port, not if the cable itself is faulty.
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Loopback plug
Why it's wrong here
A loopback plug is a diagnostic tool designed to test the functionality of a network port, such as on a Network Interface Card (NIC) or a switch. It creates a closed circuit, sending data from the port's transmit pins directly back to its receive pins to verify the port's basic transmit and receive capabilities. This tool confirms the port itself is operational, but it does not test the integrity or wiring of an external network cable run.
- ✓
Cable tester
Why this is correct
A cable tester is the appropriate tool for diagnosing faults in Ethernet cables by verifying their electrical continuity and correct wiring according to T568A or T568B standards. It identifies issues such as opens (broken wires), shorts (wires touching), crossed pairs, reversed pairs, and split pairs, which can severely impact network communication. This specialized device provides a comprehensive assessment of the cable's physical layer integrity, confirming if it meets networking specifications.
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Multimeter
Why it's wrong here
While a multimeter can measure basic electrical properties like voltage, resistance, and continuity for individual wires, it is not suitable for comprehensive Ethernet cable testing. It lacks the specialized functionality to check the complex eight-wire pinout, detect split pairs, or assess signal integrity required for network data transmission. Therefore, it cannot accurately diagnose common Ethernet cable faults that affect network performance.
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Related to this question
Learn chapter
TCP/IP and Common Ports for A+
Key term
Switch
A switch is a networking device that connects devices on a local area network and uses MAC addresses to forward data only to the intended recipient.
Key term
RJ45
RJ45 is a standardized physical connector used to plug Ethernet cables into computers, routers, switches, and other networking devices.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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