The answer is enabling full-disk encryption on the NAS. This is correct because full-disk encryption (FDE) protects data at rest by rendering all stored data unreadable without the proper decryption key, even when an attacker gains physical possession of the device. In this scenario, both the NAS and the unencrypted backup drive were stolen, but FDE on the NAS would have prevented access to the design files, financial records, and employee data. On the CISA exam, this question tests your understanding of data-at-rest encryption protection as a fundamental physical access control, often contrasted with file-level encryption or transmission controls. A common trap is assuming backup encryption alone suffices, but the key point is that both primary and backup storage must be encrypted. Memory tip: “If they steal the steel, FDE keeps the data sealed.”
CISA Protection of Information Assets Practice Question
This CISA practice question tests your understanding of protection of information assets. 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.
A small manufacturing company uses a network-attached storage (NAS) device to store design files, financial records, and employee data. The NAS is backed up weekly to an external hard drive that is stored in the same office. The company has no encryption on the NAS or the backup drive. One weekend, the office is burglarized, and both the NAS and the backup drive are stolen. The company had no remote backup. Which of the following would have best protected the data in this scenario?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enabling full-disk encryption on the NAS
Full-disk encryption (FDE) on the NAS would render the data unreadable without the decryption key, even if the physical device is stolen. Since the backup drive was also unencrypted and stored in the same location, both were equally vulnerable. FDE protects data at rest, which is the primary risk in a theft scenario where physical access is obtained.
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.
✓
Enabling full-disk encryption on the NAS
Why this is correct
Encryption renders data unreadable without the key.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Implementing strong passwords and user authentication on the NAS
Why it's wrong here
Passwords prevent unauthorized network access but not physical theft.
✗
Storing a backup offsite in a secure location
Why it's wrong here
Offsite backup aids recovery but does not protect confidentiality of stolen data.
✗
Installing a security camera and alarm system
Why it's wrong here
Surveillance deters theft but does not protect data once stolen.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose offsite backup (Option C) because it is a best practice for disaster recovery, but the question specifically asks for protection of the data in a theft scenario where both the primary and backup are stolen together, making encryption the only effective control.
Detailed technical explanation
How to think about this question
Full-disk encryption (FDE) typically uses AES-256 (Advanced Encryption Standard with 256-bit keys) and operates at the block level, encrypting every sector of the disk including the operating system, swap space, and temporary files. Without the pre-boot authentication key (e.g., a TPM chip or a passphrase), the disk appears as random noise and cannot be mounted or read. In contrast, file-level encryption only protects specific files and can leave metadata or temporary copies exposed.
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.
Protection of Information Assets — This question tests Protection of Information Assets — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enabling full-disk encryption on the NAS — Full-disk encryption (FDE) on the NAS would render the data unreadable without the decryption key, even if the physical device is stolen. Since the backup drive was also unencrypted and stored in the same location, both were equally vulnerable. FDE protects data at rest, which is the primary risk in a theft scenario where physical access is obtained.
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.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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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