The answer is defense in depth, because the company is deploying multiple layers of security controls—a firewall, an intrusion detection system (IDS), antivirus software, and security awareness training—to protect its assets. This layered approach ensures that if one control, such as the firewall, is bypassed, another layer like the IDS or antivirus can still detect or block the threat, which is the core principle of defense in depth. On the Microsoft SC-900 exam, this concept tests your understanding of how overlapping security measures create resilience, often appearing in scenario-based questions where you must identify the strategy behind combining technical, administrative, and physical controls. A common trap is confusing defense in depth with a single control like a firewall; remember that the key is redundancy across different layers. For a memory tip, think of the phrase “layers like an onion”—each layer adds protection, and peeling one away still leaves others intact.
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. A key principle to apply: defense in depth uses multiple, overlapping security controls.. 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 implements multiple layers of security controls including a firewall, an intrusion detection system (IDS), antivirus software on endpoints, and regular security awareness training for employees. This approach is an example of which security concept?
Why wrong: Zero Trust is a model that assumes no implicit trust and verifies every access request, but the scenario describes multiple layers, not just a verification framework.
B
Defense in depth
Correct. Defense in depth is the practice of layering diverse security controls to protect against threats, so that a failure in one control does not lead to a complete breach.
C
Least privilege
Why wrong: Least privilege means granting users only the permissions they need to perform their tasks; it is not about multiple layers of security.
D
Shared responsibility
Why wrong: Shared responsibility is a cloud computing model that defines which security tasks are handled by the provider versus the customer, not a layered defense approach.
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 the correct answer because the company is implementing multiple layers of security controls (firewall, IDS, antivirus, and security awareness training) to protect assets. This layered approach ensures that if one control fails, another control is in place to mitigate the threat, which is the core principle of defense in depth.
Key principle: Defense in depth uses multiple, overlapping security controls.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Zero Trust
Why it's wrong here
Zero Trust is a model that assumes no implicit trust and verifies every access request, but the scenario describes multiple layers, not just a verification framework.
✓
Defense in depth
Why this is correct
Correct. Defense in depth is the practice of layering diverse security controls to protect against threats, so that a failure in one control does not lead to a complete breach.
Related concept
Defense in depth uses multiple, overlapping security controls.
✗
Least privilege
Why it's wrong here
Least privilege means granting users only the permissions they need to perform their tasks; it is not about multiple layers of security.
✗
Shared responsibility
Why it's wrong here
Shared responsibility is a cloud computing model that defines which security tasks are handled by the provider versus the customer, not a layered defense approach.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse defense in depth with Zero Trust because both involve multiple controls, but Zero Trust specifically focuses on identity verification and least-privilege access, not just layered defenses.
Trap categories for this question
Scenario analysis trap
Zero Trust is a model that assumes no implicit trust and verifies every access request, but the scenario describes multiple layers, not just a verification framework.
Detailed technical explanation
How to think about this question
Defense in depth leverages a combination of preventive, detective, and corrective controls across physical, technical, and administrative domains. For example, a firewall (network layer) blocks unauthorized traffic, an IDS (network/detective) alerts on suspicious patterns, antivirus (endpoint) scans for malware, and security awareness training (administrative) reduces human error. In a real-world scenario, if an attacker bypasses the firewall via a phishing email, the antivirus and user training provide additional layers of defense.
KKey Concepts to Remember
Defense in depth uses multiple, overlapping security controls.
It aims to prevent a single point of failure from leading to a breach.
Layers can include physical, technical, and administrative controls.
Each layer provides a different type of protection against threats.
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
Defense in depth uses multiple, overlapping security controls.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SC-900 question in full detail.
Review defense in depth uses multiple, overlapping security controls., then practise related SC-900 questions on the same topic to reinforce the concept.
Describe the concepts of security, compliance, and identity — This question tests Describe the concepts of security, compliance, and identity — Defense in depth uses multiple, overlapping security controls..
What is the correct answer to this question?
The correct answer is: Defense in depth — Defense in depth is the correct answer because the company is implementing multiple layers of security controls (firewall, IDS, antivirus, and security awareness training) to protect assets. This layered approach ensures that if one control fails, another control is in place to mitigate the threat, which is the core principle of defense in depth.
What should I do if I get this SC-900 question wrong?
Review defense in depth uses multiple, overlapping security controls., then practise related SC-900 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Defense in depth uses multiple, overlapping security controls.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company implements multiple layers of security controls, including firewalls, antivirus software, access controls, and security awareness training. Which security concept does this approach best represent?
easy
A.Zero Trust
✓ B.Defense in depth
C.Shared responsibility
D.Least privilege
Why B: Defense in depth is the correct concept because it involves layering multiple independent security controls—such as firewalls, antivirus, access controls, and training—so that if one layer fails, others continue to protect the asset. This approach reduces the likelihood of a single point of failure and is a foundational strategy in cybersecurity architecture.
Variation 2. A company implements multiple layers of security controls: firewalls at the perimeter, intrusion detection systems on internal segments, antivirus software on all workstations, and encryption for sensitive data at rest and in transit. This strategy is intended to ensure that if one control fails, others still provide protection. Which security concept does this approach represent?
easy
A.Least privilege
✓ B.Defense in depth
C.Separation of duties
D.Zero trust
Why B: Defense in depth is the correct concept because it involves implementing multiple layers of security controls (e.g., firewalls, IDS, antivirus, encryption) so that if one layer fails, subsequent layers continue to provide protection. This layered approach ensures redundancy and mitigates the risk of a single point of failure, aligning with the scenario described.
Last reviewed: Jun 11, 2026
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