- A
The UEFI firmware has become corrupted and needs reflashing.
Why wrong: Firmware corruption would typically prevent booting or cause more severe errors, not just a checksum warning with date/time loss.
- B
The motherboard's CMOS battery is depleted or failing.
The CMOS battery maintains the BIOS settings and real-time clock when the system is off; a failing battery causes checksum errors and loss of date/time.
- C
The power supply unit is not providing enough standby power.
Why wrong: While a failing PSU can cause issues, the CMOS battery is a separate, dedicated power source for the BIOS settings; the PSU's +5VSB rail is not used for this purpose.
- D
The hard drive is failing and corrupting the boot sector.
Why wrong: A failing hard drive would cause boot or data errors, not CMOS checksum errors or date/time resets.
Quick Answer
The answer is a depleted or failing CMOS battery. This is correct because the CMOS checksum error occurs when the BIOS verifies the stored configuration data against a calculated checksum and finds a mismatch, indicating the settings have become corrupted or lost. Since the date and time reset every time the system loses power, the volatile CMOS memory—which relies on the battery to retain these settings when the computer is off—is not receiving power. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of the motherboard’s real-time clock and CMOS storage; a common trap is to suspect a failing hard drive or a corrupted BIOS chip, but the date/time reset after power-off is the key clue. Remember the memory tip: “If the clock forgets the time, the battery is past its prime.”
220-1101 BIOS / UEFI Practice Question
This 220-1201 practice question tests your understanding of bios / uefi. 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.
During a system boot, a user sees an error message: 'CMOS checksum error - Defaults loaded.' The system then boots normally but loses the date and time settings after power-off. What is the most likely hardware failure?
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 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 motherboard's CMOS battery is depleted or failing.
The CMOS checksum error indicates that the BIOS settings are corrupted or not being retained. The date/time resetting after power-off points to a failing or dead CMOS battery, which powers the volatile memory that stores these settings when the system is off.
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 UEFI firmware has become corrupted and needs reflashing.
Why it's wrong here
Firmware corruption would typically prevent booting or cause more severe errors, not just a checksum warning with date/time loss.
- ✓
The motherboard's CMOS battery is depleted or failing.
Why this is correct
The CMOS battery maintains the BIOS settings and real-time clock when the system is off; a failing battery causes checksum errors and loss of date/time.
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 power supply unit is not providing enough standby power.
Why it's wrong here
While a failing PSU can cause issues, the CMOS battery is a separate, dedicated power source for the BIOS settings; the PSU's +5VSB rail is not used for this purpose.
- ✗
The hard drive is failing and corrupting the boot sector.
Why it's wrong here
A failing hard drive would cause boot or data errors, not CMOS checksum errors or date/time resets.
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.
What to study next
Got this wrong? Here's your next step.
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.
- →
BIOS / UEFI — study guide chapter
Learn the concepts, then practise the questions
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BIOS / UEFI practice questions
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CompTIA A+ Core 1 220-1201 study guide
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220-1201 practice test guide
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FAQ
Questions learners often ask
What does this 220-1201 question test?
BIOS / UEFI — This question tests BIOS / UEFI — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The motherboard's CMOS battery is depleted or failing. — The CMOS checksum error indicates that the BIOS settings are corrupted or not being retained. The date/time resetting after power-off points to a failing or dead CMOS battery, which powers the volatile memory that stores these settings when the system is off.
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.
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 →
Same concept, more angles
1 more ways 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 user complains that their computer boots slowly and shows a 'Press F1 to continue' message every time. The firmware settings appear to have lost their configuration. What is the most likely cause?
medium- A.The boot order is incorrect
- ✓ B.The CMOS battery is failing
- C.The hard drive is failing
- D.The BIOS version is outdated
Why B: A failing or depleted CMOS battery cannot retain BIOS settings, causing defaults to load and often requiring user intervention at boot. This is a common issue that leads to the 'Press F1' prompt. The question tests understanding of CMOS battery function in maintaining firmware settings.
Last reviewed: Jun 18, 2026
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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