The answer is fail-safe defaults, as the exhibit’s iptables rules enforce a default DROP policy on the INPUT chain, meaning any packet not explicitly permitted is automatically denied. This technical concept, often called the default deny principle, ensures that if a rule is missing or a firewall fails, the system remains secure by blocking all traffic unless it is specifically allowed. On the ISC2 Certified in Cybersecurity CC exam, this principle tests your understanding of how access controls operate at a foundational level—look for a default policy of DROP or REJECT in iptables, which directly illustrates fail-safe defaults. A common trap is confusing this with least privilege, but remember: least privilege limits permissions for users or processes, while fail-safe defaults dictate the system’s baseline action when no rule matches. For a memory tip, think “deny by default, allow by exception”—if the firewall’s default is to drop, you’re seeing fail-safe defaults in action.
ISC2 CC Security Principles Practice Question
This CC practice question tests your understanding of security principles. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
Network Topology
The exhibit shows the current iptables rules. Which security principle is most clearly enforced by the default policy?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Fail-safe defaults
The default policy is DROP on the INPUT chain, meaning any traffic not explicitly allowed is denied. This is a 'fail-safe defaults' or 'default deny' principle. Option B is correct. Option A (least privilege) is about minimal permissions, but the default policy is about default action. Option C (separation of duties) is not shown. Option D (defense in depth) is not directly demonstrated.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
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 defaults
Why this is correct
The default drop policy ensures that any unapproved traffic is blocked, which is a fail-safe default.
Related concept
Authentication checks who the user is.
✗
Defense in depth
Why it's wrong here
Defense in depth would require multiple layers; only one is shown.
✗
Separation of duties
Why it's wrong here
Separation of duties is about dividing tasks, not firewall rules.
✗
Least privilege
Why it's wrong here
While related, least privilege focuses on granting minimal access, whereas the default deny policy is the foundation.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Trap categories for this question
Command / output trap
Defense in depth would require multiple layers; only one is shown.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
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. Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC question in full detail.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related CC questions on access control and AAA configuration.
Security Principles — This question tests Security Principles — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Fail-safe defaults — The default policy is DROP on the INPUT chain, meaning any traffic not explicitly allowed is denied. This is a 'fail-safe defaults' or 'default deny' principle. Option B is correct. Option A (least privilege) is about minimal permissions, but the default policy is about default action. Option C (separation of duties) is not shown. Option D (defense in depth) is not directly demonstrated.
What should I do if I get this CC question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related CC questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.