- A
Mirror backup
Why wrong: Mirror creates an exact copy, not just changes.
- B
Differential backup
Correct. Differential copies all changes since the last full backup.
- C
Full backup
Why wrong: Full backup copies all data regardless of changes.
- D
Incremental backup
Why wrong: Incremental copies changes since the last backup of any type.
Question 755 of 984
CISA Practice Question: Information Systems Operations and Business Resilience
This CISA practice question tests your understanding of information systems operations and business resilience. 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.
Which of the following backup types copies only data that has changed since the last full backup?
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
✓
Differential backup
A differential backup copies all data that has changed since the last full backup, regardless of how many incremental backups have been performed. This means each differential backup contains all changes accumulated since the most recent full backup, making it larger than an incremental backup but faster to restore (requiring only the full backup plus the latest differential).
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.
- ✗
Mirror backup
Why it's wrong here
Mirror creates an exact copy, not just changes.
- ✓
Differential backup
Why this is correct
Correct. Differential copies all changes since the last full backup.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Full backup
Why it's wrong here
Full backup copies all data regardless of changes.
- ✗
Incremental backup
Why it's wrong here
Incremental copies changes since the last backup of any type.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'differential' with 'incremental' because both copy changed data, but the key differentiator is the reference point: differential uses the last full backup, while incremental uses the last backup of any type.
Detailed technical explanation
How to think about this question
Under the hood, backup software tracks the archive bit (on Windows) or modification timestamps (on Unix/Linux) to determine changed files. In a differential strategy, the archive bit is not cleared after a differential backup, so subsequent differentials accumulate all changes since the last full backup. This contrasts with incremental backups, which clear the archive bit after each run, ensuring only changes since the last incremental are captured. In real-world scenarios, differential backups are preferred when restore speed is critical (e.g., daily backups for a database server) because only two tapes or files are needed for recovery.
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 CISA 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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Information Systems Operations and Business Resilience — study guide chapter
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FAQ
Questions learners often ask
What does this CISA question test?
Information Systems Operations and Business Resilience — This question tests Information Systems Operations and Business Resilience — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Differential backup — A differential backup copies all data that has changed since the last full backup, regardless of how many incremental backups have been performed. This means each differential backup contains all changes accumulated since the most recent full backup, making it larger than an incremental backup but faster to restore (requiring only the full backup plus the latest differential).
What should I do if I get this CISA 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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Last reviewed: Jul 4, 2026
This CISA practice question is part of Courseiva's free ISACA 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 CISA exam.
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