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ISC2 CC Practice Question: Designing a new authentication system for remote…
A company is designing a new authentication system for remote employees. They want to ensure that if one authentication factor is compromised, the system remains secure. Which security principle should they apply?
⚠ Common exam trap
ISC2 often tests the distinction between defense in depth and fail-safe, where candidates mistakenly choose fail-safe because they think it means 'safe if one factor fails,' but fail-safe is about system failure modes, not layered authentication.
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 involves implementing multiple layers of security controls so that if one authentication factor is compromised, other layers still protect the system. In this scenario, requiring multiple authentication factors (e.g., password plus biometric or token) ensures that a single compromised factor does not grant full access, maintaining overall system security.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Fail-safe
Why it's wrong here
Fail-safe defaults to a secure state on failure, which does not prevent compromise of one factor from granting access. It is tempting because it protects availability and integrity during faults, and would be correct for a system needing to deny access when a component fails, not for multi-factor resilience.
- ✗
Least privilege
Why it's wrong here
Least privilege limits account permissions, not authentication factors, so a compromised credential still grants access; the scenario requires multiple independent factors. It tempts because it reduces breach impact, and would be correct when scoping what an authenticated user may access after login.
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Need to know
Why it's wrong here
Need to know restricts access to information based on job requirements, not authentication strength, so compromising one factor still authenticates the attacker. It tempts because it limits data exposure, and would be correct when deciding which records an already-authenticated employee may view.
- ✓
Defense in depth
Why this is correct
Defense in depth layers multiple independent controls, so compromise of one factor does not defeat the whole system. That directly satisfies the stem's constraint that the system remains secure when a single authentication factor is compromised, unlike relying on one mechanism alone.
Go deeper
Related to this question
Learn chapter
Secure Network Architecture and Design
Key term
Multifactor Authentication
Multifactor Authentication (MFA) is a security method that requires you to provide two or more pieces of evidence to prove your identity before accessing an account or system.
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.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CC practice question is part of Courseiva's free ISC2 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 CC exam.