Quick Answer
The answer is the fail-safe principle. This principle ensures that when a server fails, it defaults to a secure state—such as closing all ports and denying all access—rather than an insecure one, thereby preventing a security breach. In the context of server failure, a fail-safe design guarantees that a fault condition does not inadvertently expose data or allow unauthorized entry, directly addressing the requirement that a system remains secure even when components break down. On the ISC2 Certified in Cybersecurity CC exam, this concept tests your understanding of secure design fundamentals; a common trap is confusing fail-safe with fail-open, where a failure grants access instead of blocking it. Remember the memory tip: “Fail safe, lock the gate; fail open, tempt fate.”
This CC practice question tests your understanding of security principles. 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 wants to ensure that if a server fails, it does not cause a security breach. Which principle should guide the design?
Defense in depth
Why wrong: Defense in depth is about multiple layers.
Fail-safe
Correct. The system should fail securely.
Default deny
Why wrong: Default deny applies to access decisions, not failure modes.
Least privilege
Why wrong: Least privilege is about permissions.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Fail-safe
Fail-safe ensures that when a server fails, it defaults to a secure state (e.g., closed ports, denied access) rather than an insecure one. This prevents a security breach by guaranteeing that failure does not inadvertently expose data or allow unauthorized access. In the CC exam, this principle is directly tied to designing systems that remain secure even under fault conditions.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Defense in depth
Why it's wrong here
Defense in depth is about multiple layers.
Fail-safe
Why this is correct
Correct. The system should fail securely.
Related concept
Read the scenario before looking for a memorised answer.
Default deny
Why it's wrong here
Default deny applies to access decisions, not failure modes.
Least privilege
Why it's wrong here
Least privilege is about permissions.
Common exam traps
ISC2 often tests fail-safe by contrasting it with 'fail-open' scenarios, where candidates mistakenly think a failed server should continue operating (e.g., allowing traffic) to maintain availability, but the principle prioritizes security over availability in failure states.
Detailed technical explanation
Under the hood, fail-safe often involves hardware or software failover mechanisms that trigger a 'safe mode'—for example, a Cisco ASA firewall failing open (allowing traffic) vs. failing closed (blocking traffic). In security design, fail-safe typically means failing closed, so that a crashed server drops all connections and denies access, preventing data leakage. A real-world scenario is a RADIUS server failure causing network access to be denied by default, rather than granting unauthenticated access.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
What to study next
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FAQ
Security Principles — This question tests Security Principles — Read the scenario before looking for a memorised answer..
The correct answer is: Fail-safe — Fail-safe ensures that when a server fails, it defaults to a secure state (e.g., closed ports, denied access) rather than an insecure one. This prevents a security breach by guaranteeing that failure does not inadvertently expose data or allow unauthorized access. In the CC exam, this principle is directly tied to designing systems that remain secure even under fault conditions.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
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.
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