- A
Create a NAT Gateway in a public subnet, and add a default route (0.0.0.0/0) to the NAT Gateway in the private subnet's route table.
This allows outbound internet access while blocking inbound connections.
- B
Launch a proxy server in the public subnet and configure the private instances to use it for outbound traffic.
Why wrong: This is more complex and not the recommended AWS approach for simple outbound internet access.
- C
Set up a VPN connection to an on-premises network and route all internet traffic through the VPN.
Why wrong: This does not provide direct internet access; it routes traffic to on-premises.
- D
Attach an Internet Gateway to the VPC and add a default route (0.0.0.0/0) to the Internet Gateway in the private subnet's route table.
Why wrong: This would make the private instances reachable from the internet, violating the requirement.
Quick Answer
The correct answer is to create a NAT Gateway in a public subnet and add a default route (0.0.0.0/0) to it in the private subnet’s route table. This works because the NAT Gateway, residing in a public subnet with an Elastic IP, enables outbound internet connectivity for private instances while blocking any unsolicited inbound traffic, as it only translates responses to initiated requests. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of how to architect outbound-only internet access for private subnets, often appearing in questions about secure VPC designs or hybrid networking. A common trap is confusing a NAT Gateway with a NAT Instance or assuming a NAT Gateway can be placed in a private subnet—it cannot, as it requires a public subnet for its Elastic IP. For a memory tip, remember: NAT Gateway lives in the public subnet, but its route lives in the private subnet’s route table.
ANS-C01 Network Implementation Practice Question
This ANS-C01 practice question tests your understanding of network implementation. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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 is deploying a new VPC with both public and private subnets. The public subnet hosts an internet-facing Application Load Balancer (ALB), and the private subnet hosts EC2 instances running a web application. The EC2 instances need to download updates from the internet, but they must not be directly accessible from the internet. Which combination of steps should a network engineer implement to meet these requirements?
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
Create a NAT Gateway in a public subnet, and add a default route (0.0.0.0/0) to the NAT Gateway in the private subnet's route table.
A NAT Gateway in a public subnet allows EC2 instances in private subnets to initiate outbound traffic to the internet (e.g., for updates) while preventing any unsolicited inbound connections from the internet. Adding a default route (0.0.0.0/0) to the NAT Gateway in the private subnet's route table directs all outbound internet traffic through the NAT Gateway, which translates the private IPs to the NAT Gateway's Elastic IP. This meets the requirement of internet access for downloads without direct internet accessibility.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Create a NAT Gateway in a public subnet, and add a default route (0.0.0.0/0) to the NAT Gateway in the private subnet's route table.
Why this is correct
This allows outbound internet access while blocking inbound connections.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Launch a proxy server in the public subnet and configure the private instances to use it for outbound traffic.
Why it's wrong here
This is more complex and not the recommended AWS approach for simple outbound internet access.
- ✗
Set up a VPN connection to an on-premises network and route all internet traffic through the VPN.
Why it's wrong here
This does not provide direct internet access; it routes traffic to on-premises.
- ✗
Attach an Internet Gateway to the VPC and add a default route (0.0.0.0/0) to the Internet Gateway in the private subnet's route table.
Why it's wrong here
This would make the private instances reachable from the internet, violating the requirement.
Common exam traps
Common exam trap: answer the scenario, not the keyword
AWS often tests the misconception that an Internet Gateway in a private subnet's route table provides outbound-only access, but in reality, an Internet Gateway enables bidirectional traffic, making instances publicly reachable if they have public IPs or if the route is present.
Detailed technical explanation
How to think about this question
A NAT Gateway operates at Layer 3/4, performing source network address translation (SNAT) by replacing the source IP of outbound packets with its own Elastic IP and tracking stateful connections so that return traffic is correctly forwarded to the private instance. It is deployed in a specific Availability Zone and is resilient within that zone, but for high availability across zones, you should deploy one NAT Gateway per AZ. The NAT Gateway cannot be used for IPv6 traffic; for IPv6 outbound-only internet access, you would use an egress-only Internet Gateway.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
What to study next
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FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Implementation — This question tests Network Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a NAT Gateway in a public subnet, and add a default route (0.0.0.0/0) to the NAT Gateway in the private subnet's route table. — A NAT Gateway in a public subnet allows EC2 instances in private subnets to initiate outbound traffic to the internet (e.g., for updates) while preventing any unsolicited inbound connections from the internet. Adding a default route (0.0.0.0/0) to the NAT Gateway in the private subnet's route table directs all outbound internet traffic through the NAT Gateway, which translates the private IPs to the NAT Gateway's Elastic IP. This meets the requirement of internet access for downloads without direct internet accessibility.
What should I do if I get this ANS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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 →
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. A company is deploying a VPC with both public and private subnets. They have an EC2 instance in a private subnet that needs to access the internet for software updates. Which AWS service should be placed in a public subnet to enable this?
easy- A.Internet gateway
- B.VPC endpoint
- C.Direct Connect virtual interface
- ✓ D.NAT gateway
Why D: A NAT gateway (or NAT instance) in a public subnet allows instances in private subnets to initiate outbound traffic to the internet while preventing inbound traffic from the internet. Option A is correct. Option B is incorrect because an internet gateway is in a VPC but does not allow private instances to initiate outbound traffic without a NAT. Option C is incorrect because a VPC endpoint is for private connectivity to AWS services, not internet access. Option D is incorrect because a Direct Connect virtual interface is for hybrid connectivity, not internet access.
Variation 2. A company is setting up a VPC with both public and private subnets. The private subnets need outbound internet access for software updates. Which component is required to enable this?
easy- ✓ A.A NAT gateway in a public subnet.
- B.A VPN connection to an on-premises network that has internet access.
- C.A VPC peering connection to a VPC that has internet access.
- D.An internet gateway attached to the VPC with a route in the private subnet's route table pointing to the internet gateway.
Why A: Option A is correct because a NAT gateway in a public subnet provides outbound internet access to instances in private subnets. Option B is wrong because an internet gateway does not provide outbound access for private subnets without a NAT device. Option C is wrong because VPC peering is for connecting VPCs, not internet access. Option D is wrong because a VPN connection is for site-to-site connectivity, not internet access.
Last reviewed: Jun 30, 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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