The correct answer is least privilege, as the default DROP policy on a firewall or access control list embodies the principle of minimizing access by denying all traffic unless explicitly permitted. This default deny stance ensures that no access is granted by default, forcing administrators to open only the specific ports, protocols, or services required for legitimate operations, thereby reducing the attack surface. On the ISC2 Certified in Cybersecurity CC exam, this concept tests your understanding of how security controls implement the least privilege principle through a deny-all baseline, often appearing in scenario-based questions about firewall rules or system permissions. A common trap is confusing default deny with separation of duties or defense in depth, but remember that least privilege is about granting the minimum necessary access, not about dividing responsibilities or layering defenses. To lock it in, think of the mnemonic “Deny All, Allow Only What’s Needed” — DAOWN — which directly ties default deny to the core of least privilege.
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.
Exhibit
iptables -P INPUT DROP
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
Refer to the exhibit. The security principle demonstrated by the default policy is:
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Least privilege
Correct: A - Least privilege. The default DROP policy denies all traffic by default, allowing only explicitly permitted services, which follows the principle of least privilege. Options B, C, and D do not describe default deny.
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.
✗
Separation of duties
Why it's wrong here
Separation of duties divides responsibilities among people.
✗
Defense in depth
Why it's wrong here
Defense in depth requires multiple layers, not just a default policy.
✗
Need to know
Why it's wrong here
Need to know restricts data access, not network access.
✓
Least privilege
Why this is correct
Default deny restricts access to only what is explicitly allowed, embodying least privilege.
Related concept
Authentication checks who the user is.
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.
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: Least privilege — Correct: A - Least privilege. The default DROP policy denies all traffic by default, allowing only explicitly permitted services, which follows the principle of least privilege. Options B, C, and D do not describe default deny.
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.
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