SC-900 Practice Question: Describe the concepts of security, compliance, and identity
A security architect is designing a defense strategy for a company's IT infrastructure. The strategy includes deploying a network firewall, using an intrusion detection system, installing antivirus software on all endpoints, and requiring multi-factor authentication for all user accounts. The architect explains that if the firewall fails, the IDS can detect an intrusion, and if the IDS misses something, the antivirus might catch it, and MFA can protect even if credentials are compromised. Which security principle best describes this layered approach?
⚠ Common exam trap
Watch out — candidates often confuse 'Defense in depth' with 'Zero Trust' because both involve multiple controls, but Zero Trust is specifically about continuous verification and micro-segmentation, not the layered redundancy described in the scenario.
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 the correct principle because it describes a layered security strategy where multiple independent controls (firewall, IDS, antivirus, MFA) are deployed so that if one layer fails, another layer can still prevent or detect an attack. This approach explicitly relies on redundancy and diversity of controls to provide resilience against failures or bypasses, as illustrated by the architect's explanation of how each subsequent layer compensates for potential gaps in the previous one.
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 a security strategy that employs a series of layered and overlapping security controls to protect assets. The principle is that if one security control fails or is bypassed, another control will be in place to prevent or detect an attack. This multi-layered approach, encompassing administrative, technical, and physical safeguards, significantly enhances an organization's overall resilience against diverse threats, ensuring no single point of failure compromises security.
- ✗
Least privilege
Why it's wrong here
Least privilege is an access control principle requiring that users, processes, or programs be granted only the minimum necessary permissions to perform their legitimate functions. Its primary goal is to reduce the attack surface and limit the potential damage from a compromised account or system. While crucial for security, it is a principle of access management, not a strategy for deploying multiple, overlapping security controls across different infrastructure layers.
When this WOULD be correct
A question asks: 'Which security principle ensures that users have only the access rights necessary to perform their job functions?' In that context, least privilege would be the correct answer.
- ✗
Zero Trust
Why it's wrong here
Zero Trust is a security model founded on the principle of "never trust, always verify," regardless of whether the user or device is inside or outside the traditional network perimeter. It mandates strict identity verification for every access request, continuous authorization, and micro-segmentation. While it enhances security significantly by eliminating implicit trust, it is a paradigm shift in access control and verification, not a direct strategy for deploying multiple, overlapping security layers across an infrastructure.
When this WOULD be correct
A question that asks: 'A company implements a policy where every access request is authenticated, authorized, and encrypted regardless of the network location, and no device is trusted by default. Which security principle does this represent?' In that scenario, Zero Trust would be the correct answer.
- ✗
Shared responsibility
Why it's wrong here
The shared responsibility model is a framework primarily used in cloud computing that delineates security obligations between the cloud service provider (CSP) and the customer. The CSP is typically responsible for the security of the cloud (e.g., physical infrastructure, hypervisor), while the customer is responsible for security in the cloud (e.g., data, applications, network configuration). This model clarifies accountability but does not describe a layered defense strategy itself.
When this WOULD be correct
An exam question might ask: 'A company uses a cloud provider for infrastructure. The provider secures the physical data center, while the company configures access controls and encrypts data. Which principle does this illustrate?' In that context, shared responsibility is correct.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The SC-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓Defense in depthCorrect answer▾
Why this is correct
Defense in depth is a security strategy that employs a series of layered and overlapping security controls to protect assets. The principle is that if one security control fails or is bypassed, another control will be in place to prevent or detect an attack. This multi-layered approach, encompassing administrative, technical, and physical safeguards, significantly enhances an organization's overall resilience against diverse threats, ensuring no single point of failure compromises security.
✗Least privilegeWrong answer — click to see why▾
Why this is wrong here
The question describes multiple overlapping security controls (firewall, IDS, antivirus, MFA) working together, which is the essence of defense in depth. Least privilege focuses on granting only necessary permissions, not layering controls.
★ When this WOULD be the correct answer
A question asks: 'Which security principle ensures that users have only the access rights necessary to perform their job functions?' In that context, least privilege would be the correct answer.
Why candidates choose this
Candidates may confuse 'layered' with 'restrictive' and think that limiting privileges is part of the layered approach, but least privilege is about access control, not defense layers.
✗Zero TrustWrong answer — click to see why▾
Why this is wrong here
The question describes multiple overlapping security controls (firewall, IDS, antivirus, MFA) working together, which is the essence of defense in depth, not Zero Trust. Zero Trust is a security model that assumes no implicit trust and requires continuous verification, but it is not specifically about layering multiple independent defenses.
★ When this WOULD be the correct answer
A question that asks: 'A company implements a policy where every access request is authenticated, authorized, and encrypted regardless of the network location, and no device is trusted by default. Which security principle does this represent?' In that scenario, Zero Trust would be the correct answer.
Why candidates choose this
Candidates may confuse Zero Trust with defense in depth because both involve multiple security measures. However, Zero Trust focuses on eliminating implicit trust and verifying every access, while defense in depth is about layering independent defenses to provide redundancy.
✗Shared responsibilityWrong answer — click to see why▾
Why this is wrong here
The question describes multiple overlapping security controls (firewall, IDS, antivirus, MFA) working together, which is the essence of defense in depth. Shared responsibility refers to the division of security tasks between a cloud provider and customer, not a layered defense strategy.
★ When this WOULD be the correct answer
An exam question might ask: 'A company uses a cloud provider for infrastructure. The provider secures the physical data center, while the company configures access controls and encrypts data. Which principle does this illustrate?' In that context, shared responsibility is correct.
Why candidates choose this
Candidates may confuse 'shared responsibility' with 'layered defense' because both involve multiple parties or layers, but shared responsibility is about dividing security duties between provider and customer, not stacking controls.
Analysis generated from the official SC-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
Core Security Concepts
Key term
Defense in depth
Defense in depth is a cybersecurity strategy that uses multiple layers of security controls to protect information and systems, so if one layer fails, another layer is already in place to stop the attack.
Key term
Security strategy
A security strategy is a high-level plan that outlines how an organization protects its information assets, aligns security with business goals, and manages risk over time.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.