AWS Certified Solutions Architect – Professional — Question 321

An ecommerce company has an order processing application it wants to migrate to AWS. The application has inconsistent data volume patterns, but needs to be avail at all times. Orders must be processed as they occur and in the order that they are received.
Which set of steps should a solutions architect take to meet these requirements?

Answer options

• A. Use AWS Transfer for SFTP and upload orders as they occur. Use On-Demand Instances in multiple Availability Zones for processing.
• B. Use Amazon SNS with FIFO and send orders as they occur. Use a single large Reserved Instance for processing.
• C. Use Amazon SQS with FIFO and send orders as they occur. Use Reserved Instances in multiple Availability Zones for processing.
• D. Use Amazon SQS with FIFO and send orders as they occur. Use Spot Instances in multiple Availability Zones for processing.

Correct answer: C

Explanation

Amazon SQS with FIFO is the ideal service to ensure that orders are processed strictly in the order they are received. Utilizing Reserved Instances across multiple Availability Zones guarantees the continuous availability required for the application, unlike Spot Instances which can be interrupted. AWS Transfer for SFTP and Amazon SNS are incorrect because they do not natively support the queueing and sequential processing requirements needed here.