The correct answer is HTTP and HTTPS only. This is because the ACL explicitly permits TCP traffic destined for 10.0.0.1 on ports 80 and 443, which correspond to HTTP and HTTPS, while an implicit deny any rule at the end of the ACL silently blocks all other traffic, including ICMP, SSH, or any other protocol. On the ISC2 Certified in Cybersecurity CC exam, this question tests your understanding of how ACLs filter traffic based on source, destination, and port numbers, often using a simple permit statement followed by the default deny—a common trap is forgetting that ACLs end with an implicit deny unless a permit any is explicitly added. A helpful memory tip: “Permit the port, deny the rest—ACLs are a whitelist, not a blacklist.”
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.
Exhibit
access-list 100 permit tcp any host 10.0.0.1 eq 80
access-list 100 permit tcp any host 10.0.0.1 eq 443
access-list 100 deny ip any any
Refer to the exhibit. Given the ACL shown, which traffic is allowed to reach 10.0.0.1?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
HTTP and HTTPS only.
The ACL permits TCP traffic to destination 10.0.0.1 with destination port numbers 80 (HTTP) and 443 (HTTPS). Since the ACL ends with an implicit deny any, only HTTP and HTTPS traffic is allowed to reach 10.0.0.1. Option B is correct because the ACL explicitly permits these two services.
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.
✗
No traffic is allowed.
Why it's wrong here
The first two permits allow some traffic.
✓
HTTP and HTTPS only.
Why this is correct
Permit statements for ports 80 and 443 allow HTTP and HTTPS.
Related concept
Read the scenario before looking for a memorised answer.
✗
Only traffic from the internal network.
Why it's wrong here
The ACL does not restrict by source network; it allows any.
✗
All TCP traffic from any source.
Why it's wrong here
Only TCP traffic to ports 80 and 443 is permitted.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the implicit deny any at the end of ACLs, leading candidates to forget that only explicitly permitted traffic is allowed, and that the ACL does not block traffic based on source network unless specified.
Detailed technical explanation
How to think about this question
Standard ACLs evaluate source IP only, but extended ACLs (like this one) evaluate source, destination, protocol, and port. The 'eq' keyword matches the exact port number; to match a range, you would use 'range'. The implicit deny any at the end of every ACL is a fundamental security principle that blocks all traffic not explicitly permitted.
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 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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. 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.
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: HTTP and HTTPS only. — The ACL permits TCP traffic to destination 10.0.0.1 with destination port numbers 80 (HTTP) and 443 (HTTPS). Since the ACL ends with an implicit deny any, only HTTP and HTTPS traffic is allowed to reach 10.0.0.1. Option B is correct because the ACL explicitly permits these two services.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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