The answer is a scratched or damaged drum unit. This is correct because the drum is the component that transfers the toner image onto the paper, and any physical defect—such as a scratch or nick—will pick up excess toner and deposit it as a vertical black streak in the exact same position on every page. On the CompTIA A+ Core 1 220-1201 exam, this question tests your ability to distinguish between drum-related defects and other common laser printer issues like a dirty corona wire or a failing fuser, which produce different patterns such as repeating marks or smudging. A common trap is confusing these streaks with a toner cartridge problem, but remember that toner cartridges cause fading or uneven coverage, not consistent vertical lines. For a quick memory tip, think “drum damage equals dark, repeating streaks,” and visualize a scratched record skipping in the same groove each time.
220-1201 Printer Troubleshooting Practice Question
This 220-1201 practice question tests your understanding of printer troubleshooting. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A user reports that their laser printer is producing pages with vertical black streaks. The streaks appear in the same position on every page. Which component is most likely the cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Drum unit is scratched or damaged.
Vertical black streaks on laser printer output that repeat in the same position are typically caused by a scratched or damaged drum. The drum carries the toner image, and any defect transfers toner to the paper in a repeating pattern.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Toner cartridge is low on toner.
Why it's wrong here
Low toner usually causes faded or light print, not distinct black streaks.
✓
Drum unit is scratched or damaged.
Why this is correct
A scratched drum picks up excess toner and deposits it as a repeating streak on each page.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
Fuser assembly is malfunctioning.
Why it's wrong here
A faulty fuser typically causes toner smudging or poor adhesion, not vertical streaks.
✗
Pickup rollers are worn out.
Why it's wrong here
Worn pickup rollers cause paper jams or misfeeds, not print quality defects like streaks.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 220-1201 NAT questions on configuration and troubleshooting.
Printer Troubleshooting — This question tests Printer Troubleshooting — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Drum unit is scratched or damaged. — Vertical black streaks on laser printer output that repeat in the same position are typically caused by a scratched or damaged drum. The drum carries the toner image, and any defect transfers toner to the paper in a repeating pattern.
What should I do if I get this 220-1201 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 220-1201 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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 user reports that their laser printer is producing pages with vertical black streaks. The streaks appear in the same location on every page, even after cleaning the glass and performing a calibration. Which component is most likely causing this issue?
easy
A.Fuser assembly
✓ B.Toner cartridge drum
C.Pickup rollers
D.Transfer roller
Why B: Vertical black streaks on laser printer output that repeat in the same location typically indicate a damaged drum or a scratched organic photoconductor (OPC) drum. The drum is responsible for transferring toner to the paper, and any defect on its surface will reproduce the streak on every page.
Last reviewed: Jun 18, 2026
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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.
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