mediumMultiple ChoiceObjective-mapped
First Tool for No Link Light: Cable Tester
A technician is troubleshooting a network drop that was working yesterday but now has no link light at the switch. The cable run is 80 meters and passes through a conduit. Which tool should be used first to isolate the problem?
Quick Answer
The answer is a cable tester. When troubleshooting a network drop with no link light, the most direct first tool is a cable tester because it can immediately identify physical faults like breaks, shorts, or miswiring that would prevent a link from establishing. In this scenario, the 80-meter run through a conduit introduces potential for physical damage, and a cable tester isolates the problem faster than any other tool. On the CompTIA A+ Core 1 220-1201 exam, this question tests your ability to prioritize basic troubleshooting steps—a common trap is reaching for a tone generator or multimeter first, but those are for tracing cables or measuring voltage, not for verifying continuity. Remember the memory tip: “No link? Think link—cable tester first.”
⚠ Common exam trap
The trap here is that candidates often jump to a TDR (Option D) because they think of distance-to-fault for a long run, but the question asks for the first tool to isolate the problem, and a simple cable tester is faster and more appropriate for verifying basic connectivity before using specialized equipment.
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
✓
A cable tester.
A cable tester (often a wiremap tester) is the first tool to use when verifying basic connectivity and physical layer issues like broken wires, shorts, or miswiring. Since the link light is absent and the cable was working before, the most likely cause is a physical fault in the 80-meter run, and a cable tester can quickly confirm continuity and pinout without requiring advanced diagnostics.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A tone generator and probe.
Why it's wrong here
This is used to identify which cable goes where, not to test for faults.
- ✗
A multimeter.
Why it's wrong here
A multimeter can test continuity but is less efficient than a dedicated cable tester for Ethernet cables.
- ✓
A cable tester.
Why this is correct
A cable tester can check for continuity, shorts, and wiring faults, which is the first step in diagnosing a no-link issue.
- ✗
A time-domain reflectometer (TDR).
Why it's wrong here
A TDR is more advanced and used for locating breaks or impedance issues, but a basic cable tester is sufficient for initial checks.
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
Go deeper
Related to this question
Learn chapter
Mobile Device Connectivity
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
Key term
Cable tester
A cable tester is a device used to verify that network or electrical cables are wired correctly and can carry signals without interruption.
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This 220-1201 question is part of Courseiva's 972-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on 220-1201
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A technician is troubleshooting a network drop that was working yesterday but now has no link light. The cable run is 90 meters and uses Cat5e. The patch cables and switch ports have been tested and are fine. What is the most likely issue?
medium- A.The cable is too long for Cat5e.
- ✓ B.The cable has been cut or damaged.
- C.The network switch is not powered on.
- D.The cable is terminated with the wrong standard.
Why B: Since the cable run is 90 meters (within the 100-meter maximum for Cat5e), the patch cables and switch ports are verified working, and the link light is absent, the most likely cause is physical damage to the cable—such as a cut, pinch, or break—that interrupts the electrical continuity required for link pulses. A damaged cable prevents the switch and NIC from establishing a link, even if all other components are functional.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1201 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1201 exam.