hardMultiple ChoiceObjective-mapped
220-1201 Practice Question: A technician is troubleshooting intermittent…
A technician is troubleshooting intermittent packet loss on a critical link between two buildings. The link uses single-mode fiber optic cable. Which tool is specifically designed to measure the length of the fiber and locate breaks or splices that could cause signal loss?
⚠ Common exam trap
Candidates often mistakenly choose a light meter when the question asks for locating breaks or splices, confusing total loss measurement with event location.
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
✓
OTDR
An Optical Time-Domain Reflectometer (OTDR) is the correct tool because it sends a series of light pulses into the fiber and measures the backscattered and reflected light to calculate fiber length, locate breaks, splices, and connectors, and quantify loss at each event. This makes it ideal for troubleshooting intermittent packet loss caused by physical impairments in a single-mode fiber link between buildings.
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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Light meter
Why it's wrong here
A light meter, also known as an optical power meter, is primarily used to measure the total optical power level at the end of a fiber optic link. While it can confirm the presence of light and quantify overall signal attenuation, it provides no information about the specific location or nature of faults within the fiber, such as breaks, sharp bends, or poor splices, which are critical for diagnosing intermittent packet loss.
- ✓
OTDR
Why this is correct
An Optical Time-Domain Reflectometer (OTDR) is the correct tool for diagnosing intermittent packet loss on a fiber optic link because it injects pulses of light into the fiber and measures the reflections and backscatter over time. This allows it to create a graphical trace that precisely identifies the distance to and magnitude of events such as splices, connectors, sharp bends, and breaks, providing comprehensive insight into the fiber's physical integrity and pinpointing the source of signal degradation.
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Multimeter
Why it's wrong here
A multimeter is an electrical testing device designed to measure fundamental electrical properties like voltage, current (amperage), and resistance in electrical circuits. Fiber optic cables transmit data using light pulses, not electrical signals, making a multimeter entirely unsuitable for any diagnostic or measurement task related to fiber optic infrastructure. It lacks the necessary optical components and measurement capabilities to interact with or test fiber optic media.
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Cable tester
Why it's wrong here
Standard cable testers, often referred to as LAN cable testers or continuity testers, are specifically engineered for copper-based networking cables like Unshielded Twisted Pair (UTP) or Shielded Twisted Pair (STP) Ethernet. These devices verify wire map, continuity, and sometimes length for electrical conductors. They are fundamentally incompatible with fiber optic cables, which operate on optical principles and require specialized equipment to test light transmission and physical characteristics, not electrical continuity.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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