AWS Certified Solutions Architect – Professional — Question 715

A company operates quick-service restaurants. The restaurants follow a predictable model with high sales traffic for 4 hours daily. Sales traffic is lower outside of those peak hours.
The point of sale and management platform is deployed in the AWS Cloud and has a backend that is based on Amazon DynamoDB. The database table uses provisioned throughput mode with 100,000 RCUs and 80,000 WCUs to match known peak resource consumption.
The company wants to reduce its DynamoDB cost and minimize the operational overhead for the IT staff.
Which solution meets these requirements MOST cost-effectively?

Answer options

• A. Reduce the provisioned RCUs and WCUs.
• B. Change the DynamoDB table to use on-demand capacity.
• C. Enable Dynamo DB auto scaling for the table.
• D. Purchase 1-year reserved capacity that is sufficient to cover the peak load for 4 hours each day.

Correct answer: C

Explanation

DynamoDB auto scaling automatically adjusts provisioned RCUs and WCUs based on actual traffic, which perfectly matches the predictable peak and off-peak cycle while keeping operational overhead low. On-demand capacity (Option B) is less cost-effective for high, predictable peak volumes because its per-request pricing is higher than provisioned capacity. Reserved capacity (Option D) is billed continuously 24/7, making it an inefficient choice for a workload that only peaks for 4 hours a day.