- A
The security group for the EC2 instance does not allow outbound traffic.
Why wrong: Incorrect: The engineer verified that security groups allow outbound traffic, so this is not the issue.
- B
The route table associated with the NAT gateway's subnet does not have a route to an internet gateway.
Why wrong: Incorrect: The engineer verified that the public subnet's route table has a route to the internet gateway, so this is not the issue.
- C
The route table for the private subnet does not have a route to the NAT gateway.
Correct: If the private subnet's route table does not have a route pointing 0.0.0.0/0 to the NAT gateway, traffic from the EC2 instance cannot reach the NAT gateway. Despite the engineer adding a route, it may not be correctly associated or configured.
- D
The NAT gateway does not have an Elastic IP address assigned.
Why wrong: Incorrect: The engineer verified that the NAT gateway has an Elastic IP address, so this is not the issue.
NAT Gateway Troubleshooting — Missing Internet Gateway Route in NAT Subnet
This ANS-C01 practice question tests your understanding of network design. 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 download patches from the internet. The company has created a NAT gateway in the public subnet and added a route in the private subnet's route table pointing 0.0.0.0/0 to the NAT gateway. However, the EC2 instance cannot reach the internet. The network engineer verifies that the NAT gateway has an Elastic IP address, the security group and network ACLs allow outbound traffic, and the route table for the public subnet has a route to an internet gateway. What is the most likely cause of the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 route table for the private subnet does not have a route to the NAT gateway.
The scenario states that a route pointing 0.0.0.0/0 to the NAT gateway was added to the private subnet's route table, but if that route table is not properly associated with the private subnet, or if the route was added but the target is incorrect (e.g., pointing to the wrong NAT gateway ID), the EC2 instance will not be able to send traffic through the NAT gateway. The verification that the route exists might have been insufficient. Option C points out that the route table for the private subnet does not have a route to the NAT gateway, which would directly cause the issue. The other options are contradicted by the verification steps performed by the engineer.
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 security group for the EC2 instance does not allow outbound traffic.
Why it's wrong here
Incorrect: The engineer verified that security groups allow outbound traffic, so this is not the issue.
- ✗
The route table associated with the NAT gateway's subnet does not have a route to an internet gateway.
Why it's wrong here
Incorrect: The engineer verified that the public subnet's route table has a route to the internet gateway, so this is not the issue.
- ✓
The route table for the private subnet does not have a route to the NAT gateway.
Why this is correct
Correct: If the private subnet's route table does not have a route pointing 0.0.0.0/0 to the NAT gateway, traffic from the EC2 instance cannot reach the NAT gateway. Despite the engineer adding a route, it may not be correctly associated or configured.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
- ✗
The NAT gateway does not have an Elastic IP address assigned.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The engineer verified that the public subnet's route table has a route to the IGW, but the problem might be that the private subnet's route table is missing the route to the NAT gateway, or the route is misconfigured. Always check that the route table associated with the private subnet has a default route pointing to the NAT gateway's ID.
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
- Route Table
- Internet Gateway
- Private Subnet
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.
- →
Network Design — study guide chapter
Learn the concepts, then practise the questions
- →
Network Design practice questions
Targeted practice on this topic area only
- →
All ANS-C01 questions
1,705 questions across all exam domains
- →
AWS Certified Advanced Networking Specialty ANS-C01 study guide
Full concept coverage aligned to exam objectives
- →
ANS-C01 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related ANS-C01 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Network Management and Operations practice questions
Practise ANS-C01 questions linked to Network Management and Operations.
Network Security, Compliance and Governance practice questions
Practise ANS-C01 questions linked to Network Security, Compliance and Governance.
Network Design practice questions
Practise ANS-C01 questions linked to Network Design.
Network Implementation practice questions
Practise ANS-C01 questions linked to Network Implementation.
ANS-C01 fundamentals practice questions
Practise ANS-C01 questions linked to ANS-C01 fundamentals.
ANS-C01 scenario practice questions
Practise ANS-C01 questions linked to ANS-C01 scenario.
ANS-C01 troubleshooting practice questions
Practise ANS-C01 questions linked to ANS-C01 troubleshooting.
Practice this exam
Start a free ANS-C01 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Design — This question tests Network Design — NAT Gateway.
What is the correct answer to this question?
The correct answer is: The route table for the private subnet does not have a route to the NAT gateway. — The scenario states that a route pointing 0.0.0.0/0 to the NAT gateway was added to the private subnet's route table, but if that route table is not properly associated with the private subnet, or if the route was added but the target is incorrect (e.g., pointing to the wrong NAT gateway ID), the EC2 instance will not be able to send traffic through the NAT gateway. The verification that the route exists might have been insufficient. Option C points out that the route table for the private subnet does not have a route to the NAT gateway, which would directly cause the issue. The other options are contradicted by the verification steps performed by the engineer.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
NAT Gateway
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Keep practising
More ANS-C01 practice questions
- A financial services company has a VPC with a public subnet and a private subnet. EC2 instances in the private subnet ne…
- A company is designing a network security architecture for a multi-account environment using AWS Transit Gateway. The se…
- A company is using AWS Direct Connect to connect its on-premises network to AWS. The company wants to encrypt all traffi…
- A company uses AWS Transit Gateway to connect multiple VPCs and on-premises networks via AWS Site-to-Site VPN. The secur…
- A company runs a web application on EC2 instances behind an Application Load Balancer (ALB). The application must be acc…
- A global e-commerce company uses a hub-and-spoke network topology with a transit VPC in us-east-1. Each spoke VPC has an…
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.