mediumMultiple ChoiceObjective-mapped
ISC2 CC Practice Question: Refer to the exhibit
Exhibit
rule id=10 action=deny source=any destination=any service=http,https rule id=20 action=allow source=internal_network destination=any service=http,https rule id=30 action=allow source=any destination=dmz service=http
Refer to the exhibit. A network administrator configured the following firewall rules. After implementation, users from the internal network cannot browse the internet. Which element is causing the issue?
⚠ Common exam trap
ISC2 often tests the concept that ACL rule order is critical — candidates mistakenly think that a permit rule later in the list can override an earlier deny, but the first-match principle means the deny is evaluated first and blocks the traffic permanently.
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
✓
The rule order
The issue is the rule order. Firewall rules are processed sequentially from top to bottom. Rule id=20 denies all traffic from the internal network, and it appears before rule id=30 which permits HTTP/HTTPS. Because rules are evaluated in order, the deny rule (id=20) matches first and blocks all internet-bound traffic before the permit rule (id=30) is reached. Therefore, the correct answer is D: the rule order is causing the problem.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Rule id=30
Why it's wrong here
Rule 30 is for DMZ traffic and does not affect internal internet browsing.
- ✗
Rule id=10
Why it's wrong here
The rule itself is not wrong; its placement is the issue.
- ✗
Rule id=20
Why it's wrong here
Rule 20 correctly allows internal traffic, but it is never reached.
- ✓
The rule order
Why this is correct
The deny rule should be after the allow rule to permit internal traffic first.
Visual reference
Go deeper
Related to this question
Learn chapter
Network Security Foundations
Key term
Hypertext Transfer Protocol Secure
Hypertext Transfer Protocol Secure, or HTTPS, is the secure version of HTTP that encrypts data between a web browser and a website using SSL/TLS to protect sensitive information like passwords and credit card numbers.
Key term
Firewall
A firewall is a network security system that monitors and controls incoming and outgoing traffic based on predetermined security rules to protect trusted internal networks from untrusted external networks.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.