AWS Certified Solutions Architect – Professional — Question 690

A company is running an application in the AWS Cloud. The application consists of microservices that run on a fleet of Amazon EC2 instances in multiple
Availability Zones behind an Application Load Balancer. The company recently added a new REST API that was implemented in Amazon API Gateway. Some of the older microservices that run on EC2 instances need to call this new API.
The company does not want the API to be accessible from the public internet and does not want proprietary data to traverse the public internet.
What should a solutions architect do to meet these requirements?

Answer options

• A. Create an AWS Site-to-Site VPN connection between the VPC and the API Gateway. Use API Gateway to generate a unique API key for each microservice. Configure the API methods to require the key.
• B. Create an interface VPC endpoint for API Gateway, and set an endpoint policy to only allow access to the specific API. Add a resource policy to API Gateway to only allow access from the VPC endpoint. Change the API Gateway endpoint type to private.
• C. Modify the API Gateway to use IAM authentication Update the IAM policy for the IAM role that is assigned to the EC2 instances to allow access to the API Gateway Move the API Gateway into a new VPC. Deploy a transit gateway and connect the VPCs.
• D. Create an accelerator in AWS Global Accelerator, and connect the accelerator to the API Gateway. Update the route table for all VPC subnets with a route to the created Global Accelerator endpoint IP address. Add an API key for each service to use for authentication.

Correct answer: B

Explanation

To prevent traffic from traversing the public internet and keep the API private, the API Gateway endpoint type must be set to private. Creating an interface VPC endpoint (powered by AWS PrivateLink) allows the EC2 instances inside the VPC to securely connect to API Gateway using private IP addresses. Applying endpoint and resource policies ensures that only the specified VPC endpoint can access the REST API, satisfying all security requirements.