AWS Certified Solutions Architect – Associate (SAA-C03) — Question 328

A company needs to migrate a legacy application from an on-premises data center to the AWS Cloud because of hardware capacity constraints. The application runs 24 hours a day, 7 days a week. The application’s database storage continues to grow over time.

What should a solutions architect do to meet these requirements MOST cost-effectively?

Answer options

• A. Migrate the application layer to Amazon EC2 Spot Instances. Migrate the data storage layer to Amazon S3.
• B. Migrate the application layer to Amazon EC2 Reserved Instances. Migrate the data storage layer to Amazon RDS On-Demand Instances.
• C. Migrate the application layer to Amazon EC2 Reserved Instances. Migrate the data storage layer to Amazon Aurora Reserved Instances.
• D. Migrate the application layer to Amazon EC2 On-Demand Instances. Migrate the data storage layer to Amazon RDS Reserved Instances.

Correct answer: C

Explanation

Since the legacy application runs continuously (24/7), using Amazon EC2 Reserved Instances is the most cost-effective choice for the application layer because Spot instances can be interrupted and On-Demand instances are more expensive. For the database layer, Amazon Aurora automatically scales storage as it grows, and purchasing Aurora Reserved Instances ensures the lowest cost for a steady-state 24/7 database workload.