The answer is disabling unused ports and services, along with using strong, complex passwords for firewall administration and applying the principle of least privilege. Disabling unused ports reduces the attack surface by eliminating unnecessary entry points that attackers could exploit, as each open port—like leaving TCP 23 for Telnet active—creates a potential vector for unauthorized access. On the ISC2 Certified in Cybersecurity CC exam, this concept tests your understanding of fundamental network hardening and the principle of least privilege, often appearing in multiple-select questions where a common trap is confusing “blocking all traffic” with “disabling unused services” (the latter is the precise best practice). Remember the memory tip: “Close what you don’t use, lock what you do”—if a port isn’t serving a business need, shut it down to shrink the attack surface.
ISC2 CC Security Operations Practice Question
This CC practice question tests your understanding of security operations. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which THREE of the following are best practices for securing a network firewall? (Select THREE.)
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Disable unused services and ports
Disabling unused services and ports reduces the attack surface by eliminating potential entry points for attackers. A firewall should only have necessary ports (e.g., TCP 80/443 for web traffic) open, as each open service represents a vector for exploitation. This aligns with the principle of least privilege and is a fundamental hardening step.
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.
✓
Disable unused services and ports
Why this is correct
Reduces the attack surface.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Allow all traffic by default and block specific threats
Why it's wrong here
Default deny is the secure practice; default allow is insecure.
✓
Implement rule change management and review
Why this is correct
Ensures changes are authorized and auditable.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Place the firewall outside the network perimeter
Why it's wrong here
Firewall should be at the perimeter, not outside the network.
✓
Use strong, complex passwords for firewall administration
Why this is correct
Prevents unauthorized administrative access.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the misconception that a firewall should be placed outside the network perimeter for better visibility, but the correct placement is at the perimeter to filter traffic before it enters the internal network.
Detailed technical explanation
How to think about this question
Firewalls operate using stateful inspection or packet filtering rules; disabling unused services often involves closing TCP/UDP ports in the access control list (ACL) and removing associated application-layer inspection rules. In a real-world scenario, a firewall left with default open ports like Telnet (TCP 23) or SNMP (UDP 161) could be scanned and exploited, leading to unauthorized administrative access or network reconnaissance.
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 security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC question in full detail.
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Disable unused services and ports — Disabling unused services and ports reduces the attack surface by eliminating potential entry points for attackers. A firewall should only have necessary ports (e.g., TCP 80/443 for web traffic) open, as each open service represents a vector for exploitation. This aligns with the principle of least privilege and is a fundamental hardening step.
What should I do if I get this CC question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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.