The answer is that a differential backup copies files changed since the last full backup. This is correct because a differential backup does not track every incremental change; instead, it captures all data that has been modified relative to the most recent full backup, making it larger than an incremental backup but faster to restore. On the ISC2 Certified in Cybersecurity CC exam, this concept tests your understanding of backup strategies and recovery sequences, often appearing in questions about disaster recovery or data integrity. A common trap is confusing differential with incremental backups—remember that incremental backs up changes since the last backup of any type, while differential always references the last full backup. To recover, you must restore the full backup first, then apply the single differential file. Memory tip: think of “differential” as “different from full”—it only holds what’s different since the last full backup.
ISC2 CC Business Continuity, DR & Incident Response Practice Question
This CC practice question tests your understanding of business continuity, dr & incident response. 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 TWO are true about a differential backup? (Select two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It requires a full backup to be restored first
A differential backup copies all files that have changed since the last full backup. Because it does not contain the complete data set, you must first restore the most recent full backup and then apply the differential backup on top of it to recover the system. This makes option B correct.
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.
✗
It copies files changed since the last backup of any type
Why it's wrong here
That describes an incremental backup.
✓
It requires a full backup to be restored first
Why this is correct
The full backup must be restored before applying the differential.
Related concept
Read the scenario before looking for a memorised answer.
✓
It copies files changed since the last full backup
Why this is correct
This is the defining characteristic of differential backups.
Related concept
Read the scenario before looking for a memorised answer.
✗
It resets the archive bit on backed-up files
Why it's wrong here
Resetting the archive bit is done by incremental backups, not differential.
✗
It is faster to restore than a full backup
Why it's wrong here
Restoring a differential requires first restoring the full backup, then the differential, so it is slower.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the distinction between differential and incremental backups by making candidates confuse 'changed since last full' (differential) with 'changed since last backup of any type' (incremental), and by implying that differential backups reset the archive bit when they do not.
Detailed technical explanation
How to think about this question
Under the hood, the archive bit (or file attribute) is used by backup software to track changes. A full backup clears the archive bit on all files, a differential backup reads files with the archive bit set but does not clear it, and an incremental backup both reads and clears the archive bit. In a real-world scenario, if you run a full backup on Sunday and differential backups Monday through Friday, Friday's differential contains all changes since Sunday, making it larger than Monday's but requiring only two restore steps (full + Friday's differential) instead of six (full + five incrementals).
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 SOC analyst notices unusual lateral movement in the network at 2 AM. The IR playbook dictates: identify and contain (isolate the affected machine), then eradicate (remove the malware), then recover (restore from backup), then document. Skipping containment before eradication risks the attacker regaining access. Questions like this test the sequence and rationale of incident response phases.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC question in full detail.
Business Continuity, DR & Incident Response — This question tests Business Continuity, DR & Incident Response — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: It requires a full backup to be restored first — A differential backup copies all files that have changed since the last full backup. Because it does not contain the complete data set, you must first restore the most recent full backup and then apply the differential backup on top of it to recover the system. This makes option B correct.
What should I do if I get this CC 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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