SC-900 Defense in depth Practice Question
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?
⚠ Common exam trap
Many candidates 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.
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 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.
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 security model that operates on the principle of "never trust, always verify," meaning no user, device, or application is implicitly trusted, regardless of its location within or outside the network perimeter. Every access request is rigorously authenticated, authorized, and continuously validated based on all available data points, including user identity, device health, and service context. While Zero Trust architectures may leverage multiple security controls, its fundamental focus is on dynamic access validation rather than simply implementing diverse security layers for general protection.
When this WOULD be correct
A question that asks: 'A company requires all users to authenticate and be authorized for every access attempt, regardless of whether they are inside or outside the network. This approach is an example of which security concept?' would make Zero Trust the correct answer.
- ✓
Defense in depth
Why this is correct
Defense in depth is a cybersecurity strategy that employs multiple, independent layers of security controls to protect information and systems. The objective is to ensure that if one security control fails or is bypassed, other controls are in place to prevent or delay a breach, thereby increasing the overall resilience of the system. This layered approach often includes a combination of technical controls like firewalls and intrusion detection systems, administrative controls such as policies and training, and physical controls.
- ✗
Least privilege
Why it's wrong here
The principle of least privilege dictates that users, applications, and systems should be granted only the minimum necessary permissions and access rights required to perform their legitimate functions. This approach significantly reduces the potential attack surface and limits the "blast radius" if an account or system is compromised, preventing unauthorized lateral movement or data exfiltration. While a critical security practice, least privilege focuses on the scope of access for individual entities, not on implementing multiple, diverse security controls across an entire infrastructure.
When this WOULD be correct
A question that asks: 'A company configures user accounts so that employees can only access files required for their job roles. This approach is an example of which security concept?' would make least privilege the correct answer.
- ✗
Shared responsibility
Why it's wrong here
Shared responsibility describes a cloud security model where the provider and customer divide tasks, but this scenario involves only on-premises controls—firewall, IDS, antivirus, and training—all managed solely by the company, with no cloud provider involved. It is tempting because the phrase “multiple layers” can evoke the idea of shared duties across teams, but shared responsibility specifically applies to cloud service agreements (e.g., Microsoft Entra ID tenant security), not to a single organisation’s layered defence stack.
When this WOULD be correct
In a scenario where a company uses a cloud service provider and the question asks who is responsible for securing the operating system, data, or physical infrastructure, shared responsibility would be the correct answer. For example: 'A company uses Azure IaaS. Who is responsible for patching the guest OS?'
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 cybersecurity strategy that employs multiple, independent layers of security controls to protect information and systems. The objective is to ensure that if one security control fails or is bypassed, other controls are in place to prevent or delay a breach, thereby increasing the overall resilience of the system. This layered approach often includes a combination of technical controls like firewalls and intrusion detection systems, administrative controls such as policies and training, and physical controls.
✗Zero TrustWrong answer — click to see why▾
Why this is wrong here
Zero Trust is a security model that assumes no implicit trust and requires continuous verification for every access request, but the question describes multiple layers of security controls, which is the definition of defense in depth, not Zero Trust.
★ When this WOULD be the correct answer
A question that asks: 'A company requires all users to authenticate and be authorized for every access attempt, regardless of whether they are inside or outside the network. This approach is an example of which security concept?' would make Zero Trust the correct answer.
Why candidates choose this
Candidates may confuse Zero Trust with defense in depth because both involve multiple security measures, but Zero Trust specifically focuses on eliminating implicit trust and verifying every access, not just layering controls.
✗Least privilegeWrong answer — click to see why▾
Why this is wrong here
The question describes multiple layers of security controls (firewall, IDS, antivirus, training), which is the definition of defense in depth, not least privilege. Least privilege restricts user access rights to only what is necessary, which is not illustrated here.
★ When this WOULD be the correct answer
A question that asks: 'A company configures user accounts so that employees can only access files required for their job roles. This approach is an example of which security concept?' would make least privilege the correct answer.
Why candidates choose this
Candidates may confuse the layered approach with the principle of least privilege because both involve multiple security measures, but least privilege specifically focuses on minimal access rights, not layered defenses.
✗Shared responsibilityWrong answer — click to see why▾
Why this is wrong here
The question describes multiple security layers (firewall, IDS, antivirus, training), which is the definition of defense in depth. Shared responsibility is a cloud model where the provider and customer share security duties, not a multi-layered on-premises approach.
★ When this WOULD be the correct answer
In a scenario where a company uses a cloud service provider and the question asks who is responsible for securing the operating system, data, or physical infrastructure, shared responsibility would be the correct answer. For example: 'A company uses Azure IaaS. Who is responsible for patching the guest OS?'
Why candidates choose this
Candidates may confuse the idea of multiple security layers with the concept of dividing security tasks between parties, especially if they recall that 'defense in depth' involves layers and mistakenly think 'shared responsibility' also implies layers.
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
Threat
A threat is any potential danger that could harm a computer system, network, or data, whether from a malicious hacker, a natural disaster, or an accidental mistake.
Key term
Security
Security in IT is the practice of protecting systems, networks, and data from unauthorized access, damage, or theft.
About these practice questions
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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.