- A
Defense in depth
Defense in depth is the correct concept. It employs overlapping security controls so that if one layer is breached, subsequent layers continue to protect the system.
- B
Least privilege
Why wrong: Least privilege is about granting users the minimum permissions needed to perform their tasks, not about layered controls.
- C
Separation of duties
Why wrong: Separation of duties prevents a single individual from having excessive control by splitting critical actions among multiple people, not by layering defenses.
- D
Zero trust
Why wrong: Zero trust is a security model that requires continuous verification of every access request, treating all users as potential threats even if inside the network. It is not the same as deploying multiple security layers.
Quick Answer
The answer is defense in depth, the correct security concept for this layered approach. This strategy is correct because it deliberately deploys multiple independent controls—such as firewalls, intrusion detection systems, and endpoint antivirus—across different network layers, ensuring that if one control fails or is breached, others remain intact to block or mitigate the threat. On the Microsoft SC-900 exam, this concept tests your understanding of how redundancy and layering prevent a single point of failure from compromising the entire security posture; a common trap is confusing defense in depth with a single strong control like a next-generation firewall, but the key is the intentional stacking of diverse defenses. To remember it, think of an onion: each layer adds protection, and peeling one away still leaves the core safe.
SC-900 Practice Question: Describe the concepts of security, compliance, and identity
This SC-900 practice question tests your understanding of describe the concepts of security, compliance, and identity. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 company deploys firewalls, intrusion detection systems, and endpoint antivirus software at multiple layers of its network. This strategy is intended to ensure that if one security control fails, others still provide protection. Which security concept does this approach represent?
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
Defense in depth
Defense in depth is a security strategy that layers multiple independent controls—such as firewalls, intrusion detection systems (IDS), and endpoint antivirus—across different network segments. The core principle is that if one layer is breached or fails, subsequent layers continue to provide protection, ensuring no single point of failure compromises the entire security posture.
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.
- ✓
Defense in depth
Why this is correct
Defense in depth is the correct concept. It employs overlapping security controls so that if one layer is breached, subsequent layers continue to protect the system.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Least privilege
Why it's wrong here
Least privilege is about granting users the minimum permissions needed to perform their tasks, not about layered controls.
- ✗
Separation of duties
Why it's wrong here
Separation of duties prevents a single individual from having excessive control by splitting critical actions among multiple people, not by layering defenses.
- ✗
Zero trust
Why it's wrong here
Zero trust is a security model that requires continuous verification of every access request, treating all users as potential threats even if inside the network. It is not the same as deploying multiple security layers.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse 'defense in depth' with 'zero trust' because both involve multiple security controls, but zero trust is specifically about eliminating implicit trust through continuous verification, not about layering independent defenses.
Detailed technical explanation
How to think about this question
In a defense-in-depth architecture, each layer addresses different attack vectors: network firewalls filter traffic at Layers 3-4 (IP/port), intrusion detection systems analyze patterns at Layer 7 (application payload), and endpoint antivirus uses signature-based and heuristic detection at the host level. A real-world scenario is a web application protected by a web application firewall (WAF) at the perimeter, a host-based IDS on the server, and file-integrity monitoring on critical databases—if the WAF misses a SQL injection, the IDS may still catch the anomalous query.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
Got this wrong? Here's your next step.
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Describe the concepts of security, compliance, and identity — study guide chapter
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FAQ
Questions learners often ask
What does this SC-900 question test?
Describe the concepts of security, compliance, and identity — This question tests Describe the concepts of security, compliance, and identity — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Defense in depth — Defense in depth is a security strategy that layers multiple independent controls—such as firewalls, intrusion detection systems (IDS), and endpoint antivirus—across different network segments. The core principle is that if one layer is breached or fails, subsequent layers continue to provide protection, ensuring no single point of failure compromises the entire security posture.
What should I do if I get this SC-900 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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Last reviewed: Jun 11, 2026
This SC-900 practice question is part of Courseiva's free Microsoft 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 SC-900 exam.
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