ANS-C01 Network Implementation Practice Question
A company has a VPC with a public subnet hosting a web server. They want to make the web server accessible over the internet. The web server has a public IP address. The public subnet route table has a default route (0.0.0.0/0) to an internet gateway. The security group for the web server allows inbound HTTP (port 80) from 0.0.0.0/0. However, external users cannot access the web server. What is the most likely cause?
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 internet gateway is not attached to the VPC
The internet gateway must be attached to the VPC. If it is not attached, traffic cannot flow. Option B (NACL) could be blocking but default NACL allows all traffic. Option C (web server not listening) is possible but less likely than IGW attachment. Option D (route table) is already correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The internet gateway is not attached to the VPC
Why this is correct
Internet gateway must be attached for public traffic.
- ✗
The web server is not listening on port 80
Why it's wrong here
Possible but not the most likely network issue.
- ✗
The route table for the public subnet does not have a route to the internet gateway
Why it's wrong here
It does have the route.
- ✗
The network ACL for the public subnet is blocking inbound HTTP traffic
Why it's wrong here
Default NACL allows all traffic.
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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.