The correct answer is Defense in Depth. This model is defined by its multi-layered security strategy, where independent controls such as perimeter firewalls, network segmentation, endpoint antivirus, data encryption, and employee training work together so that if one layer fails, others continue to protect the asset. On the SC-900 exam, this concept tests your understanding that no single control is sufficient—a common trap is confusing Defense in Depth with a single strong control like encryption alone. The exam often presents a list of varied controls and asks which model they represent; the key is recognizing the deliberate layering of different types of defenses. A helpful memory tip is to think of a castle with a moat, walls, guards, and locked doors—each layer provides a separate barrier, just like the layers in a Defense in Depth model.
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's IT department deploys a multi-layered security strategy that includes a perimeter firewall, network segmentation, endpoint antivirus software, data encryption, and employee security awareness training. Which security model does this approach represent?
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
The described approach—combining perimeter firewalls, network segmentation, endpoint antivirus, encryption, and training—is the classic definition of Defense in Depth. This model layers multiple independent security controls so that if one layer fails (e.g., a firewall rule is misconfigured), subsequent layers (e.g., segmentation, antivirus) still protect the asset. It does not assume any single control is sufficient, which is the core principle of Defense in Depth.
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.
✗
Zero Trust
Why it's wrong here
Zero Trust focuses on verifying every access request, not on multiple layers of controls.
✗
Least Privilege
Why it's wrong here
Least privilege ensures users have only necessary permissions, but is not a layered security model.
✓
Defense in Depth
Why this is correct
Defense in depth uses multiple overlapping security layers to reduce risk.
Related concept
Read the scenario before looking for a memorised answer.
✗
Shared Responsibility
Why it's wrong here
Shared responsibility describes the division of security tasks between cloud providers and customers.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates see 'firewall' and 'encryption' and immediately think Zero Trust, but Zero Trust requires explicit identity verification and micro-segmentation, not just a layered stack of traditional controls.
Detailed technical explanation
How to think about this question
Defense in Depth is often visualized as concentric rings of protection, where each ring addresses different threat vectors: network-level (firewall, IDS/IPS), host-level (antivirus, HIDS), application-level (input validation, encryption), and administrative (policies, training). In practice, this model ensures that even if an attacker bypasses the perimeter firewall via a phishing email, endpoint antivirus and data encryption still mitigate the impact. The model is formalized in standards like NIST SP 800-53, which recommends overlapping controls across management, operational, and technical domains.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SC-900 question in full detail.
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 — The described approach—combining perimeter firewalls, network segmentation, endpoint antivirus, encryption, and training—is the classic definition of Defense in Depth. This model layers multiple independent security controls so that if one layer fails (e.g., a firewall rule is misconfigured), subsequent layers (e.g., segmentation, antivirus) still protect the asset. It does not assume any single control is sufficient, which is the core principle of Defense in Depth.
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.
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 secures its network by deploying a firewall at the perimeter, an intrusion prevention system on internal segments, endpoint antivirus on all workstations, and encrypting sensitive data at rest and in transit. This layered approach ensures that if one control fails, others still provide protection. Which security concept does this strategy best represent?
easy
A.Least privilege
✓ B.Defense in depth
C.Zero Trust
D.Separation of duties
Why B: The strategy described uses multiple independent security controls—firewall, IPS, endpoint antivirus, and encryption—so that if one layer fails, others continue to protect the asset. This is the core definition of defense in depth, which creates overlapping layers of protection rather than relying on a single point of failure.
Last reviewed: Jun 11, 2026
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