ANS-C01 Network Security, Compliance and Governance Practice Question
A security engineer is designing a network ACL for a public subnet. The subnet hosts a web server on port 443. Which inbound and outbound rules should be configured to allow HTTPS traffic from the internet? (Assume default deny all rule.)
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
✓
Inbound: allow TCP 443 from 0.0.0.0/0; Outbound: allow TCP 1024-65535 to 0.0.0.0/0.
NACLs are stateless, requiring explicit inbound and outbound rules. The inbound rule allows HTTPS (TCP 443) from the internet. The outbound rule allows return traffic on ephemeral ports (1024-65535) back to the internet. Option B is wrong because the outbound rule only allows TCP 443, which is too restrictive for return traffic. Option C is wrong because the inbound rule only allows ephemeral ports, not HTTPS. Option D is wrong because it incorrectly states 'for responses' and the outbound rule is still too restrictive.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Inbound: allow TCP 443 from 0.0.0.0/0; Outbound: allow TCP 1024-65535 to 0.0.0.0/0.
Why this is correct
This allows incoming HTTPS and outgoing return traffic on ephemeral ports.
- ✗
Inbound: allow TCP 443 from 0.0.0.0/0; Outbound: allow TCP 443 to 0.0.0.0/0.
Why it's wrong here
Return traffic from the web server uses ephemeral ports, not port 443.
- ✗
Inbound: allow TCP 1024-65535 from 0.0.0.0/0; Outbound: allow TCP 443 to 0.0.0.0/0.
Why it's wrong here
This would allow incoming on ephemeral ports and outgoing on 443, which is incorrect.
- ✗
Inbound: allow TCP 443 from 0.0.0.0/0; Outbound: allow TCP 443 to 0.0.0.0/0 for responses.
Why it's wrong here
Return traffic uses high ports (1024-65535), not port 443.
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Same concept, more angles
2 more ways this is tested on ANS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Refer to the exhibit. A network engineer reviews the NACL entries for a subnet. What is the effect of this NACL on inbound traffic?
hard- ✓ A.Only SSH from the internal network and HTTPS from any IP are allowed.
- B.All inbound traffic is allowed.
- C.Only HTTPS traffic is allowed from any IP.
- D.All inbound traffic is denied.
Why A: Inbound rules: Rule 100 allows SSH from 10.0.0.0/16 (internal network). Rule 200 allows HTTPS from 0.0.0.0/0 (any IP). Rule 300 (implicit deny) denies all other inbound traffic. Therefore, only SSH from the internal network and HTTPS from any IP are allowed. Option B is incorrect because not all inbound traffic is allowed; SSH from external networks is denied. Option C is incorrect because HTTPS is allowed from anywhere. Option D is incorrect because the NACL does not deny all traffic; it allows specific traffic.
Variation 2. Refer to the exhibit. A network engineer examines the network ACL for a subnet. Which statement best describes the effect of this network ACL?
medium- A.Both inbound and outbound TCP traffic are allowed
- ✓ B.Inbound TCP traffic is allowed, but all outbound traffic is denied
- C.All inbound traffic is allowed
- D.All outbound traffic is allowed
Why B: The inbound rule explicitly allows TCP traffic (protocol 6) from any source (0.0.0.0/0). However, the outbound rules consist only of a default deny rule, which blocks all outbound traffic. Therefore, inbound TCP traffic is allowed, but all outbound traffic is denied. Option A is incorrect because outbound traffic is denied, not allowed. Option C is incorrect because only inbound TCP is allowed, not all inbound traffic. Option D is incorrect because outbound traffic is denied.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-C01 practice question is part of Courseiva's free Amazon Web Services 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 ANS-C01 exam.