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SSCP Practice Question: Which THREE of the following are examples of…
Which THREE of the following are examples of detective controls?
⚠ Common exam trap
Many exam-takers confuse preventive controls (like firewalls and encryption) with detective controls, mistakenly thinking that any security tool that 'stops' or 'protects' data also detects attacks, when in fact detective controls only identify and report incidents without blocking them.
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
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Intrusion detection system (IDS)
An intrusion detection system (IDS) is a detective control because it monitors network or host activity and generates alerts when it identifies suspicious patterns or known attack signatures, without blocking the traffic itself. A security information and event management (SIEM) system is also detective: it aggregates and correlates logs from multiple sources and applies rules or analytics to identify and alert on security incidents. Log monitoring and analysis is detective by definition, since reviewing and correlating log data (e.g., via syslog, Windows Event Log, or audit trails) is how organizations discover that an event has occurred. By contrast, data encryption at rest is a preventive control that renders stored data unreadable to unauthorized parties, and a firewall with a default-deny rule is a preventive control that blocks traffic not explicitly permitted, so neither detects incidents after the fact.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Intrusion detection system (IDS)
Why this is correct
An IDS monitors network or host activity and raises alerts when it identifies malicious patterns, identifying events after they occur rather than blocking them. This detection-after-the-fact behaviour is what classifies it as a detective control rather than a preventive one.
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Security information and event management (SIEM)
Why this is correct
SIEM aggregates and correlates log data from multiple sources, generating alerts on suspicious activity after it occurs — satisfying the detective control requirement of identifying events rather than preventing them. Unlike preventive controls such as firewalls or encryption, it provides visibility and retrospective detection, making it a valid example here.
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Data encryption at rest
Why it's wrong here
Encryption at rest is a preventive control: it stops unauthorised reading of stored data rather than identifying that an event occurred. It is tempting because it supports investigation indirectly, and would be correct where the question asked for preventive controls protecting data confidentiality on disk or backups.
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Log monitoring and analysis
Why this is correct
Log monitoring and analysis is a detective control because it identifies security events after they occur, satisfying the stem's requirement for detection rather than prevention. Reviewing logs reveals unauthorised activity, anomalies and policy violations, enabling timely response. Unlike preventive controls such as firewalls, it does not block actions; it discovers them, confirming its classification as detective.
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Firewall with default-deny rule
Why it's wrong here
A default-deny firewall is preventive; it blocks traffic rather than recording or alerting on activity that has happened. It is tempting because its logs can feed detection, and would be correct where the question asked for a preventive control restricting inbound or outbound traffic to explicitly permitted flows.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SSCP 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 SSCP exam.