AWS Certified Solutions Architect – Professional — Question 947

A Solutions Architect must design a highly available, stateless, REST service. The service will require multiple persistent storage layers for service object meta information and the delivery of content. Each request needs to be authenticated and securely processed. There is a requirement to keep costs as low as possible.
How can these requirements be met?

Answer options

• A. Use AWS Fargate to host a container that runs a self-contained REST service. Set up an Amazon ECS service that is fronted by an Application Load Balancer (ALB). Use a custom authenticator to control access to the API. Store request meta information in Amazon DynamoDB with Auto Scaling and static content in a secured S3 bucket. Make secure signed requests for Amazon S3 objects and proxy the data through the REST service interface.
• B. Use AWS Fargate to host a container that runs a self-contained REST service. Set up an ECS service that is fronted by a cross-zone ALB. Use an Amazon Cognito user pool to control access to the API. Store request meta information in DynamoDB with Auto Scaling and static content in a secured S3 bucket. Generate presigned URLs when returning references to content stored in Amazon S3.
• C. Set up Amazon API Gateway and create the required API resources and methods. Use an Amazon Cognito user pool to control access to the API. Configure the methods to use AWS Lambda proxy integrations, and process each resource with a unique AWS Lambda function. Store request meta information in DynamoDB with Auto Scaling and static content in a secured S3 bucket. Generate presigned URLs when returning references to content stored in Amazon S3.
• D. Set up Amazon API Gateway and create the required API resources and methods. Use an Amazon API Gateway custom authorizer to control access to the API. Configure the methods to use AWS Lambda custom integrations, and process each resource with a unique Lambda function. Store request meta information in an Amazon ElastiCache Multi-AZ cluster and static content in a secured S3 bucket. Generate presigned URLs when returning references to content stored in Amazon S3.

Correct answer: D

Explanation

Option D provides a highly available, serverless, and cost-effective architecture by leveraging Amazon API Gateway and AWS Lambda, which eliminates the idle hosting costs associated with running Fargate containers in Options A and B. Utilizing an Amazon API Gateway custom authorizer and custom integrations ensures secure, tailored authentication and request processing. Additionally, using ElastiCache Multi-AZ for metadata storage ensures high availability and low latency, while generating S3 presigned URLs allows clients to fetch content directly, avoiding expensive data transfer proxying costs.