- A
Separation of duties
Why wrong: Separation of duties prevents any single person from having too much control.
- B
Defense in depth
Defense in depth uses multiple overlapping controls.
- C
Fail-secure
Why wrong: Fail-secure ensures that on failure, the system defaults to a secure state.
- D
Least privilege
Why wrong: Least privilege limits access rights to minimum necessary.
Question 857 of 1,000
CISSP Software Development Security Practice Question
This CISSP practice question tests your understanding of software development security. 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 architect is designing a system that must continue to function even when a component fails. The architect implements multiple layers of security controls so that if one fails, others still provide protection. Which principle is being applied?
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 (B) is the correct principle because it involves implementing multiple layers of security controls (e.g., firewalls, intrusion detection systems, encryption, access controls) so that if one layer fails or is bypassed, other layers continue to provide protection, ensuring the system remains functional. This directly matches the scenario where the architect designs for continued operation despite component failure by layering controls.
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.
- ✗
Separation of duties
Why it's wrong here
Separation of duties prevents any single person from having too much control.
- ✓
Defense in depth
Why this is correct
Defense in depth uses multiple overlapping controls.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Fail-secure
Why it's wrong here
Fail-secure ensures that on failure, the system defaults to a secure state.
- ✗
Least privilege
Why it's wrong here
Least privilege limits access rights to minimum necessary.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse 'defense in depth' with 'fail-secure' because both involve planning for failure, but fail-secure prioritizes security over availability (e.g., locking down on failure) whereas defense in depth prioritizes continued operation through redundancy of controls.
Detailed technical explanation
How to think about this question
In practice, defense in depth leverages overlapping controls at different layers of the OSI model or application stack—for example, network-level controls (e.g., IPsec, ACLs) combined with host-level controls (e.g., SELinux, application whitelisting) and data-level controls (e.g., TLS, database encryption). A real-world scenario is a web application protected by a WAF, rate limiting, input validation, and parameterized queries; if the WAF fails, the other layers still prevent SQL injection. This principle is codified in NIST SP 800-53 as a foundational security architecture strategy.
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 developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this CISSP question test?
Software Development Security — This question tests Software Development Security — 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 (B) is the correct principle because it involves implementing multiple layers of security controls (e.g., firewalls, intrusion detection systems, encryption, access controls) so that if one layer fails or is bypassed, other layers continue to provide protection, ensuring the system remains functional. This directly matches the scenario where the architect designs for continued operation despite component failure by layering controls.
What should I do if I get this CISSP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
This CISSP 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 CISSP exam.
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