ANS-C01 Network Security, Compliance and Governance Practice Question
A company hosts a multi-tier web application in a VPC. The web servers are in a public subnet, and the application servers are in a private subnet. The application servers need to access a third-party API over the internet. The company wants to ensure that the application servers' IP addresses are not exposed to the internet, and that all outbound traffic to the internet is logged. Additionally, the company wants to restrict outbound traffic to only the specific API endpoints. Which solution should be used?
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
✓
Deploy a NAT gateway in the public subnet and add a route in the private subnet's route table pointing to the NAT gateway. Use security groups on the application servers to restrict outbound traffic to the API endpoints. Enable logs on the NAT gateway using VPC Flow Logs or NAT gateway logs.
A NAT gateway in a public subnet allows instances in private subnets to access the internet while hiding their private IPs. By controlling the outbound rules in the security group or using a network firewall, you can restrict traffic to specific API endpoints. AWS CloudWatch Logs or VPC Flow Logs can capture the NAT gateway logs. Option A is incorrect because a VPC endpoint is used for accessing AWS services privately and cannot be used for internet API access. Option B is incorrect because attaching an internet gateway directly to the private subnet would expose the instances' private IPs to the internet. Option C is incorrect because while a proxy server could work, it adds unnecessary complexity and management overhead compared to a NAT gateway.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use a VPC endpoint for the third-party API service.
Why it's wrong here
VPC endpoints are for AWS services, not third-party APIs.
- ✗
Attach an internet gateway directly to the private subnet and configure the route table to send default traffic to the internet gateway. Use security groups to restrict outbound traffic to the API endpoints. Enable VPC Flow Logs for logging.
Why it's wrong here
This would expose the private subnet instances directly to the internet, defeating the purpose of hiding IPs.
- ✗
Deploy a proxy server in the public subnet and configure the application servers to use the proxy. Restrict outbound traffic from the proxy using security groups. Log proxy access logs.
Why it's wrong here
A proxy server adds overhead and requires managing the proxy; it is not a native AWS solution.
- ✓
Deploy a NAT gateway in the public subnet and add a route in the private subnet's route table pointing to the NAT gateway. Use security groups on the application servers to restrict outbound traffic to the API endpoints. Enable logs on the NAT gateway using VPC Flow Logs or NAT gateway logs.
Why this is correct
The NAT gateway provides outbound internet access with private IPs, and security groups control traffic. Logging can be enabled via VPC Flow Logs.
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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.