AWS Certified Solutions Architect – Professional — Question 491

A company wants to refactor its retail ordering web application that currently has a load-balanced Amazon EC2 instance fleet for web hosting, database API services, and business logic. The company needs to create a decoupled, scalable architecture with a mechanism for retaining failed orders while also minimizing operational costs.
Which solution will meet these requirements?

Answer options

• A. Use Amazon S3 for web hosting with Amazon API Gateway for database API services. Use Amazon Simple Queue Service (Amazon SQS) for order queuing. Use Amazon Elastic Container Service (Amazon ECS) for business logic with Amazon SQS long polling for retaining failed orders.
• B. Use AWS Elastic Beanstalk for web hosting with Amazon API Gateway for database API services. Use Amazon MQ for order queuing. Use AWS Step Functions for business logic with Amazon S3 Glacier Deep Archive for retaining failed orders.
• C. Use Amazon S3 for web hosting with AWS AppSync for database API services. Use Amazon Simple Queue Service (Amazon SQS) for order queuing. Use AWS Lambda for business logic with an Amazon SQS dead-letter queue for retaining failed orders.
• D. Use Amazon Lightsail for web hosting with AWS AppSync for database API services. Use Amazon Simple Email Service (Amazon SES) for order queuing. Use Amazon Elastic Kubernetes Service (Amazon EKS) for business logic with Amazon Elasticsearch Service (Amazon ES) for retaining failed orders.

Correct answer: C

Explanation

Option C is correct because it leverages a fully serverless, highly decoupled architecture using Amazon S3, AWS AppSync, and AWS Lambda, which minimizes operational overhead and costs. Using an Amazon SQS dead-letter queue (DLQ) is the native and most cost-effective way to isolate and retain failed orders for troubleshooting. Other options introduce higher operational costs with container management (ECS/EKS) or use inappropriate services for queuing and failed-order retention.