- A
The NAT gateway's Elastic IP is not associated with the NAT gateway
Why wrong: This is incorrect. The problem states the NAT gateway has an Elastic IP, so it is associated. The issue lies elsewhere.
- B
The NAT gateway is not in a public subnet
This is correct. For a NAT gateway to provide internet access, it must be in a public subnet with a route to an internet gateway. If the subnet's route table does not have a 0.0.0.0/0 route pointing to an internet gateway, the NAT gateway cannot reach the internet.
- C
The private subnet's network ACL is blocking outbound traffic
Why wrong: This is incorrect. The problem states security groups and NACLs are properly configured, so they are not blocking traffic.
- D
The EC2 instance does not have a route to the internet
Why wrong: This is incorrect. The private subnet route table has a default route to the NAT gateway, so the instance does have a route to the internet.
ANS-C01 NAT Gateway Practice Question
This ANS-C01 practice question tests your understanding of network management and operations. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: nAT Gateway. 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.
A company has a VPC with a public subnet and a private subnet. An EC2 instance in the private subnet needs to access the internet for software updates. The instance is associated with an Elastic IP address. The route table for the private subnet has a default route (0.0.0.0/0) pointing to a NAT gateway. The NAT gateway is in the public subnet and has an Elastic IP. Despite this, the instance cannot reach the internet. The security groups and NACLs are properly configured. What is the 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 NAT gateway is not in a public subnet
The instance cannot reach the internet because the NAT gateway, although placed in a subnet labeled as public, is not in a functional public subnet—the subnet's route table must include a default route (0.0.0.0/0) pointing to an internet gateway. The problem statement indicates the NAT gateway has an Elastic IP, so association is not the issue. Instead, the likely cause is that the public subnet's route table lacks this route, meaning the NAT gateway cannot communicate with the internet gateway. Option A is incorrect because the NAT gateway's Elastic IP is properly associated. Option C is incorrect because NACLs are properly configured. Option D is incorrect because the private subnet route table correctly points to the NAT gateway for 0.0.0.0/0.
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's Elastic IP is not associated with the NAT gateway
- ✓
The NAT gateway is not in a public subnet
- ✗
The private subnet's network ACL is blocking outbound traffic
Why it's wrong here
This is incorrect. The problem states security groups and NACLs are properly configured, so they are not blocking traffic.
- ✗
The EC2 instance does not have a route to the internet
Why it's wrong here
This is incorrect. The private subnet route table has a default route to the NAT gateway, so the instance does have a route to the internet.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many candidates assume that placing a NAT gateway in a subnet labeled 'public' is sufficient, but the subnet must also have a route to an internet gateway to be truly public.
Detailed technical explanation
How to think about this question
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- NAT Gateway
- Public Subnet
- Internet Gateway
- Route Table
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
NAT Gateway
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Visual reference
What to study next
Got this wrong? Here's your next step.
Review nAT Gateway, then practise related ANS-C01 questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Management and Operations — This question tests Network Management and Operations — NAT Gateway.
What is the correct answer to this question?
The correct answer is: The NAT gateway is not in a public subnet — The instance cannot reach the internet because the NAT gateway, although placed in a subnet labeled as public, is not in a functional public subnet—the subnet's route table must include a default route (0.0.0.0/0) pointing to an internet gateway. The problem statement indicates the NAT gateway has an Elastic IP, so association is not the issue. Instead, the likely cause is that the public subnet's route table lacks this route, meaning the NAT gateway cannot communicate with the internet gateway. Option A is incorrect because the NAT gateway's Elastic IP is properly associated. Option C is incorrect because NACLs are properly configured. Option D is incorrect because the private subnet route table correctly points to the NAT gateway for 0.0.0.0/0.
What should I do if I get this ANS-C01 question wrong?
Review nAT Gateway, then practise related ANS-C01 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
NAT Gateway
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Last reviewed: Jun 20, 2026
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.
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