ANS-C01 Network Management and Operations Practice Question
A company uses AWS CloudFormation to deploy a VPC with public and private subnets. The template includes an Internet Gateway and a NAT Gateway. After deployment, instances in the private subnet cannot access the internet. The network engineer checks the route tables and finds that the private subnet route table has a default route pointing to the NAT Gateway. What is the most likely cause of the issue?
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 NAT Gateway is deployed in the private subnet instead of the public subnet.
The NAT Gateway must be deployed in a public subnet with a route to the Internet Gateway. If it is in a private subnet, it cannot reach the internet, so instances in the private subnet cannot use it for outbound traffic. Option B is incorrect because security groups by default allow outbound traffic. Option C is incorrect because the question states the private subnet route table has a default route pointing to the NAT Gateway. Option D is incorrect because while the NAT Gateway being in a private subnet and lacking a route to the IGW is a related issue, the most direct cause is that the NAT Gateway itself is in the wrong subnet, as stated in option A.
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 NAT Gateway is deployed in the private subnet instead of the public subnet.
Why this is correct
NAT Gateway must be in a public subnet with a route to IGW to function.
- ✗
The security group attached to the NAT Gateway blocks outbound traffic.
Why it's wrong here
NAT Gateway does not have security groups.
- ✗
The private subnet route table does not have a default route (0.0.0.0/0) to the NAT Gateway.
Why it's wrong here
The stem states the route is present.
- ✗
The NAT Gateway is in a private subnet and has no route to the internet gateway.
Why it's wrong here
The issue is the NAT Gateway placement, not its route.
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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.