This FC0-U61 practice question tests your understanding of database fundamentals. 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 database administrator notices that a transaction that updates two tables is failing halfway, leaving data inconsistent. Which property of ACID ensures that the database returns to its original state if the transaction fails?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Atomicity
Atomicity (option D) ensures that a transaction is treated as a single, indivisible unit of work. If any part of the transaction fails (e.g., updating the second table), the entire transaction is rolled back, and the database returns to its original state before the transaction began. This prevents partial updates that would leave data inconsistent.
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.
✗
Consistency
Why it's wrong here
Consistency ensures that data is valid before and after a transaction, but the rollback is due to atomicity.
✗
Durability
Why it's wrong here
Durability ensures committed transactions persist, not rollback of uncommitted ones.
✗
Isolation
Why it's wrong here
Isolation ensures concurrent transactions do not affect each other, not rollback.
✓
Atomicity
Why this is correct
Atomicity guarantees that all parts of a transaction succeed or none do, allowing rollback on failure.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the distinction between Atomicity and Consistency, where candidates mistakenly think Consistency handles rollback, but Atomicity is the property that ensures the entire transaction is undone on failure.
Detailed technical explanation
How to think about this question
Under the hood, Atomicity is implemented via a write-ahead log (WAL) or undo log. Before any changes are applied, the database records the original data in the log; if the transaction fails (e.g., due to a constraint violation or power loss), the database uses the log to revert all changes. In MySQL with InnoDB, this is managed by the redo and undo logs, where the undo log stores the before-image for rollback. A real-world scenario is a bank transfer: if the debit succeeds but the credit fails, Atomicity rolls back the debit to maintain balance integrity.
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 FC0-U61 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.
Database Fundamentals — This question tests Database Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Atomicity — Atomicity (option D) ensures that a transaction is treated as a single, indivisible unit of work. If any part of the transaction fails (e.g., updating the second table), the entire transaction is rolled back, and the database returns to its original state before the transaction began. This prevents partial updates that would leave data inconsistent.
What should I do if I get this FC0-U61 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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