- A
The keyboard driver is corrupted.
Why wrong: Driver issues typically cause no response or wrong characters from specific keys, not random characters from unrelated keys.
- B
The keyboard ribbon cable is loose.
Why wrong: A loose cable would cause some keys to not work or intermittent failure, not random character output.
- C
The keyboard has an internal short or faulty controller.
An internal short can cause ghost key presses, leading to random characters. Replacement is necessary.
- D
The operating system has a malware infection.
Why wrong: Malware can simulate keystrokes, but it would usually produce consistent patterns, not random characters on key press.
Question 673 of 1,020
Laptop Keyboard Types Random Characters: Internal Short or Faulty Controller
This 220-1201 practice question tests your understanding of mobile device hardware servicing. 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 laptop's keyboard types random characters when certain keys are pressed. The laptop has not been dropped or spilled on. What is the most likely hardware issue?
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.
Quick Answer
The answer is an internal short or faulty keyboard controller, as this is the most likely hardware issue when a laptop keyboard types random characters without any physical damage or liquid spill. This occurs because the keyboard matrix relies on a grid of circuits to register each keypress; a short circuit or a failing controller can send incorrect signals to the system, causing it to interpret a single press as multiple or random characters. On the CompTIA A+ Core 1 220-1201 exam, this question tests your ability to distinguish between hardware failures and software or driver issues—a common trap is to suspect malware or sticky keys, but the absence of spills or drops points directly to the keyboard assembly itself. Remember the memory tip: “Short circuit, wrong circuit”—if the keyboard types gibberish and the laptop is clean, the controller or matrix is the culprit, and replacement is the standard fix.
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
✓
The keyboard has an internal short or faulty controller.
Option C is correct because a keyboard with an internal short or faulty controller can cause erratic behavior like typing random characters when keys are pressed. This occurs because the short or controller failure disrupts the matrix scanning process, sending incorrect key codes to the system. Since the laptop was not dropped or spilled, physical damage like a loose ribbon cable is less likely, making an internal component failure the most probable hardware cause.
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.
- ✗
The keyboard driver is corrupted.
Why it's wrong here
Driver issues typically cause no response or wrong characters from specific keys, not random characters from unrelated keys.
- ✗
The keyboard ribbon cable is loose.
Why it's wrong here
A loose cable would cause some keys to not work or intermittent failure, not random character output.
- ✓
The keyboard has an internal short or faulty controller.
Why this is correct
An internal short can cause ghost key presses, leading to random characters. Replacement is necessary.
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.
- ✗
The operating system has a malware infection.
Why it's wrong here
Malware can simulate keystrokes, but it would usually produce consistent patterns, not random characters on key press.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The 220-1201 exam often tests the distinction between hardware and software issues, and the trap here is that candidates may confuse a loose ribbon cable (which causes missing keys) with a faulty controller (which causes random characters), as both are hardware problems but with different symptoms.
Trap categories for this question
Command / output trap
A loose cable would cause some keys to not work or intermittent failure, not random character output.
Detailed technical explanation
How to think about this question
Keyboards use a matrix circuit where each key press connects a row and column line; the controller scans these lines to determine the pressed key. An internal short can bridge multiple lines, causing the controller to interpret a single press as multiple keys or random characters. In real-world scenarios, this can also be caused by liquid residue or debris that creates conductive paths, even without a visible spill, leading to intermittent ghost typing.
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.
TExam Day Tips
- 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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this 220-1201 question test?
Mobile Device Hardware Servicing — This question tests Mobile Device Hardware Servicing — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The keyboard has an internal short or faulty controller. — Option C is correct because a keyboard with an internal short or faulty controller can cause erratic behavior like typing random characters when keys are pressed. This occurs because the short or controller failure disrupts the matrix scanning process, sending incorrect key codes to the system. Since the laptop was not dropped or spilled, physical damage like a loose ribbon cable is less likely, making an internal component failure the most probable hardware cause.
What should I do if I get this 220-1201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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Last reviewed: Jul 4, 2026
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