The answer is defense in depth, the security principle that best represents a layered strategy using multiple independent controls like firewalls, antivirus, and multi-factor authentication. This principle is correct because it explicitly relies on the concept of redundancy across diverse security layers, ensuring that if one control is bypassed or fails, subsequent layers still provide protection and prevent a single point of failure. On the Microsoft SC-900 exam, this concept tests your understanding of foundational security architecture, often appearing in scenario-based questions where a company deploys overlapping physical, technical, and administrative safeguards. A common trap is confusing defense in depth with the principle of least privilege or zero trust, but remember: defense in depth is about layers, not permissions. For a quick memory tip, think of an onion—multiple layers mean that even if one is peeled away, the core remains protected.
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 security manager explains that the company's security strategy relies on multiple layers of controls, such as firewalls, antivirus software, and multi-factor authentication, so that if one layer fails, another can still prevent an attack. Which security principle does this strategy best represent?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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 it explicitly describes a layered security strategy where multiple independent controls (firewalls, antivirus, MFA) are deployed so that if one layer is bypassed or fails, subsequent layers still provide protection. This principle is foundational to modern security architecture and directly matches the scenario of using diverse controls to prevent a single point of failure.
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 uses multiple overlapping layers of security controls to provide redundancy.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Least privilege
Why it's wrong here
Least privilege restricts user permissions to the minimum required, not layering of controls.
✗
Zero Trust
Why it's wrong here
Zero Trust is an architectural model that never trusts any request without verification, not specifically about multiple layers.
✗
Separation of duties
Why it's wrong here
Separation of duties prevents a single person from having conflicting responsibilities, not about multiple security layers.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Zero Trust with defense in depth because both involve multiple controls, but Zero Trust is specifically about verifying every access request regardless of origin, whereas defense in depth is about layering independent controls to provide redundancy and depth.
Detailed technical explanation
How to think about this question
Defense in depth leverages a combination of preventive, detective, and corrective controls at different layers of the OSI model—for example, network firewalls (Layer 3/4), host-based intrusion detection (Layer 7), and application-level MFA. In practice, this means an attacker who compromises a perimeter firewall still faces endpoint protection (e.g., Windows Defender) and authentication challenges (e.g., Azure AD MFA with conditional access policies). A real-world scenario is a ransomware attack that evades email filtering but is stopped by endpoint detection and response (EDR) because the file is quarantined before execution.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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 — Defense in depth is the correct answer because it explicitly describes a layered security strategy where multiple independent controls (firewalls, antivirus, MFA) are deployed so that if one layer is bypassed or fails, subsequent layers still provide protection. This principle is foundational to modern security architecture and directly matches the scenario of using diverse controls to prevent a single point of failure.
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.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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 a security strategy that includes multiple layers of controls: a perimeter firewall, an intrusion detection system, endpoint antivirus software, and multi-factor authentication for user access. The goal is that if one layer fails, another layer is in place to prevent or mitigate an attack. Which security principle does this approach best represent?
easy
✓ A.Defense in depth
B.Zero Trust
C.Least privilege
D.CIA triad
Why A: Defense in depth is a security strategy that layers independent defensive mechanisms so that if one layer fails, another layer is already in place to prevent or mitigate an attack. The scenario explicitly describes multiple layers (firewall, IDS, endpoint antivirus, MFA) working together, which is the core definition of defense in depth. This approach ensures no single point of failure can compromise the entire security posture.
Last reviewed: Jun 11, 2026
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