The answer is a scratched drum, as vertical black streaks on laser printer output that repeat in the same position on every page are almost always caused by a physical defect on the drum surface. The drum is a photosensitive cylinder that rotates during the printing process, transferring toner to the paper; any scratch, gouge, or wear mark on this component will pick up excess toner and deposit it as a consistent vertical line with each rotation. On the CompTIA A+ Core 1 220-1201 exam, this question tests your ability to distinguish between drum damage and other common laser printer issues like a dirty corona wire or a faulty fuser—traps often include fuser problems (which cause smearing, not repeating streaks) or toner cartridge leaks (which produce random spots). A solid memory tip is to think of the drum as a record player: a scratch on the vinyl causes the same skip every rotation, just as a scratch on the drum causes the same streak every page.
220-1201 Printer Troubleshooting Practice Question
This 220-1201 practice question tests your understanding of printer troubleshooting. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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. What is the most likely 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
✓
A scratched drum
Vertical black streaks on laser printer output are typically caused by a damaged or scratched drum. The drum rotates and transfers toner, so any defect creates a repeating mark. Cleaning or replacing the drum usually resolves the issue.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Low toner cartridge
Why it's wrong here
Low toner usually causes faded or light print, not solid black streaks.
✗
A dirty corona wire
Why it's wrong here
A dirty corona wire causes vertical white streaks or poor charge, not black marks.
✓
A scratched drum
Why this is correct
A scratched drum picks up toner and transfers it repeatedly, creating consistent vertical black streaks.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
A faulty fuser
Why it's wrong here
A faulty fuser causes toner that smears or does not bond, but not repeating black streaks.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 220-1201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
Identify which 220-1201 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Printer Troubleshooting — This question tests Printer Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A scratched drum — Vertical black streaks on laser printer output are typically caused by a damaged or scratched drum. The drum rotates and transfers toner, so any defect creates a repeating mark. Cleaning or replacing the drum usually resolves the issue.
What should I do if I get this 220-1201 question wrong?
Identify which 220-1201 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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?
Read the scenario before looking for a memorised answer.
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Question Discussion
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