- A
Data backup
Why wrong: Backup is a corrective control.
- B
Encryption
Why wrong: Encryption is a preventive control.
- C
Firewall
Why wrong: Firewall is a preventive control.
- D
Intrusion detection system
IDS detects attacks or policy violations.
Question 477 of 1,000
CRISC IT Risk Assessment Practice Question
This CRISC practice question tests your understanding of it risk assessment. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 is a detective control for an information system?
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
✓
Intrusion detection system
An intrusion detection system (IDS) is a detective control because it monitors network traffic or system activity for malicious actions or policy violations and generates alerts when such events occur. Unlike preventive controls, an IDS does not block or stop the attack; it detects and reports it after the fact, enabling incident response.
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.
- ✗
Data backup
Why it's wrong here
Backup is a corrective control.
- ✗
Encryption
Why it's wrong here
Encryption is a preventive control.
- ✗
Firewall
Why it's wrong here
Firewall is a preventive control.
- ✓
Intrusion detection system
Why this is correct
IDS detects attacks or policy violations.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing detective controls (which identify incidents after they occur) with preventive controls (which stop incidents before they happen), leading candidates to mistakenly classify firewalls or encryption as detective.
Detailed technical explanation
How to think about this question
An IDS can be network-based (NIDS) analyzing packet headers and payloads via signature-based detection (e.g., Snort rules) or anomaly-based detection using baselines. It operates out-of-band, receiving a copy of traffic (e.g., via a SPAN port or TAP), so it does not introduce latency or single-point-of-failure risks. In contrast, an intrusion prevention system (IPS) sits inline and can block traffic, making it a preventive control.
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 CRISC 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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FAQ
Questions learners often ask
What does this CRISC question test?
IT Risk Assessment — This question tests IT Risk Assessment — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Intrusion detection system — An intrusion detection system (IDS) is a detective control because it monitors network traffic or system activity for malicious actions or policy violations and generates alerts when such events occur. Unlike preventive controls, an IDS does not block or stop the attack; it detects and reports it after the fact, enabling incident response.
What should I do if I get this CRISC 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.
About these practice questions
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Last reviewed: Jul 4, 2026
This CRISC 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 CRISC exam.
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