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ANS-C01 Network Design Practice Question

A financial services company must meet PCI DSS compliance requirements. The company's VPC contains a web server in a public subnet and an application server in a private subnet. The application server must communicate with a third-party payment gateway over the internet, but the security team prohibits using an Elastic IP address or a NAT gateway due to auditing concerns. Which solution satisfies these requirements?

⚠ Common exam trap

Many candidates assume a NAT gateway or proxy is required for outbound internet access, but PrivateLink provides a private, internet-free connection to third-party services, directly addressing the auditing and compliance constraints.

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

Use AWS PrivateLink to connect to the payment gateway via a VPC Endpoint Service

AWS PrivateLink allows the application server in the private subnet to connect to the third-party payment gateway via a VPC Endpoint Service without traversing the internet, using private IP addresses. This eliminates the need for an Elastic IP address or a NAT gateway, satisfying the security team's auditing concerns while meeting PCI DSS compliance requirements.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Deploy a NAT instance in the public subnet and route traffic through it

    Why it's wrong here

    A NAT instance requires an Elastic IP address, which is prohibited by the security team.

  • Configure a proxy server in the public subnet and have the application server use the proxy

    Why it's wrong here

    A proxy server in a public subnet would typically have a public IP, which is not allowed.

  • Use AWS PrivateLink to connect to the payment gateway via a VPC Endpoint Service

    Why this is correct

    PrivateLink enables private connectivity to services over the AWS network, avoiding public IPs and internet transit, meeting compliance requirements.

  • Attach an Internet Gateway to the VPC and use a default route to 0.0.0.0/0 in the private subnet

    Why it's wrong here

    Without a NAT device, private instances cannot initiate outbound traffic to the internet even with an IGW.

Visual reference

Inside (Private) PC-A 10.0.0.1 PC-B 10.0.0.2 NAT Router Outside (Public) 203.0.113.1 Inside Global Server PAT: many private IPs share one public IP via unique port numbers

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JA

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.