The answer is anti-malware at endpoints, an Intrusion Detection System (IDS), and a firewall. These three layers form the core of a defense-in-depth strategy because they address distinct security functions: the firewall acts as the first line of perimeter defense by filtering traffic based on rules, the IDS provides a detection layer that monitors network traffic for suspicious activity and known attack signatures, alerting when the firewall is bypassed, and anti-malware protects endpoints by scanning for and blocking malicious code that evades network controls. On the Systems Security Certified Practitioner SSCP exam, this question tests your understanding of layered security controls and the difference between preventive (firewall, anti-malware) and detective (IDS) measures. A common trap is confusing an IDS with an IPS or assuming anti-malware is only a host-based control—remember that defense-in-depth requires overlapping, not redundant, layers. Memory tip: think “F-A-I” for Firewall, Anti-malware, IDS—the three pillars that block, detect, and clean.
SSCP Network and Communications Security Practice Question
This SSCP practice question tests your understanding of network and communications security. 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 network security team is implementing a defense-in-depth strategy. Which three layers should be included? (Choose three.)
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 (IDS)
An Intrusion Detection System (IDS) is a key layer in defense-in-depth because it monitors network traffic for suspicious activity and known attack signatures, providing visibility and alerting when perimeter defenses like firewalls are bypassed. It operates by analyzing packets against a rule set (e.g., Snort rules) and generating alerts, enabling a response before damage escalates. This adds a detection layer that complements preventive controls, ensuring that even if an attacker penetrates the outer defenses, the breach is identified.
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.
✓
Intrusion Detection System (IDS)
Why this is correct
An IDS monitors network traffic for malicious activity, providing a detection layer.
Related concept
Read the scenario before looking for a memorised answer.
✓
Firewall
Why this is correct
A firewall provides network perimeter protection as a prevention layer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Single sign-on (SSO)
Why it's wrong here
SSO simplifies authentication but is not a security layer; it's an access control mechanism.
✗
Physical security controls
Why it's wrong here
Physical security is important but is typically considered a separate domain; defense-in-depth often focuses on technical controls.
✓
Anti-malware at endpoints
Why this is correct
Endpoint anti-malware provides host-based protection as a prevention and detection layer.
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 that candidates often mistake Single Sign-On (SSO) for a security layer because it involves authentication, but it is an access management convenience tool, not a defensive control that protects against network or endpoint threats.
Detailed technical explanation
How to think about this question
Defense-in-depth layers operate at different points of the kill chain: firewalls filter at the network perimeter (Layer 3/4), IDS inspects traffic for anomalies (e.g., TCP SYN floods or SQL injection patterns), and endpoint anti-malware uses signature-based and heuristic analysis (e.g., YARA rules) to block execution of malicious code. In a real-world scenario, a firewall might allow HTTP traffic, an IDS detects a CVE-2021-44228 Log4j exploit attempt in the payload, and endpoint anti-malware prevents the payload from executing, demonstrating layered redundancy.
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 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
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.
Network and Communications Security — This question tests Network and Communications Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Intrusion Detection System (IDS) — An Intrusion Detection System (IDS) is a key layer in defense-in-depth because it monitors network traffic for suspicious activity and known attack signatures, providing visibility and alerting when perimeter defenses like firewalls are bypassed. It operates by analyzing packets against a rule set (e.g., Snort rules) and generating alerts, enabling a response before damage escalates. This adds a detection layer that complements preventive controls, ensuring that even if an attacker penetrates the outer defenses, the breach is identified.
What should I do if I get this SSCP 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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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.
Question Discussion
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