Quick Answer
The correct answer is the last full backup plus all incremental backups after that. This is because incremental backups only capture data changed since the most recent backup—whether full or incremental—creating a sequential chain where each link depends on the previous one. To restore the most recent clean state before ransomware encryption, you must apply every incremental in order after the last full backup; skipping any one breaks the chain and results in an incomplete or corrupted restore. On the CISSP exam, this tests your understanding of backup chain integrity and recovery point objectives, often appearing as a trap where candidates mistakenly choose only the last full backup or the latest incremental alone. A common memory tip: think of incremental backups as links in a chain—if you remove one link, the entire chain falls apart.
This CISSP practice question tests your understanding of security operations. 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.
An organization's backup strategy includes daily full backups and hourly incremental backups. The system suffers a ransomware attack that encrypts all data. Which backup set is essential to restore the most recent clean state?
The last full backup plus all incremental backups after that
Provides the most recent clean state by applying all increments.
The last full backup plus the last incremental backup
Why wrong: Missing intermediate increments; may not fully restore.
The last full backup only
Why wrong: Does not include changes after the full backup.
The last incremental backup only
Why wrong: Requires the full backup to restore from.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The last full backup plus all incremental backups after that
To restore the most recent clean state after a ransomware attack, you need the last full backup as the base and all subsequent incremental backups to apply every change made up to the moment before the attack. Incremental backups capture only data changed since the last backup (full or incremental), so skipping any breaks the chain and results in data loss. Option A correctly includes the full backup and every incremental backup after it, ensuring a complete restoration to the latest point before encryption.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The last full backup plus all incremental backups after that
Why this is correct
Provides the most recent clean state by applying all increments.
Related concept
Read the scenario before looking for a memorised answer.
The last full backup plus the last incremental backup
Why it's wrong here
Missing intermediate increments; may not fully restore.
The last full backup only
Why it's wrong here
Does not include changes after the full backup.
The last incremental backup only
Why it's wrong here
Requires the full backup to restore from.
Common exam traps
The trap here is that candidates confuse incremental backups with differential backups, mistakenly thinking only the last incremental is needed, when in fact incremental backups require the entire chain from the last full backup to restore completely.
Detailed technical explanation
Incremental backup chains rely on archive bits or change tracking mechanisms (e.g., Windows archive bit or Linux rsync timestamps) to mark only new or modified files. Restoration requires replaying each incremental in sequence from the last full backup; if any incremental is missing or corrupt, the chain breaks and data from that point forward is lost. In ransomware scenarios, attackers often target backup files, so maintaining an offline or immutable copy of the full backup and all increments is critical to ensure a clean recovery point.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
What to study next
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FAQ
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
The correct answer is: The last full backup plus all incremental backups after that — To restore the most recent clean state after a ransomware attack, you need the last full backup as the base and all subsequent incremental backups to apply every change made up to the moment before the attack. Incremental backups capture only data changed since the last backup (full or incremental), so skipping any breaks the chain and results in data loss. Option A correctly includes the full backup and every incremental backup after it, ensuring a complete restoration to the latest point before encryption.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This CISSP practice question is part of Courseiva's free ISC2 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 CISSP exam.
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