AWS Certified Solutions Architect – Associate (SAA-C03) — Question 745

A company's web application that is hosted in the AWS Cloud recently increased in popularity. The web application currently exists on a single Amazon EC2 instance in a single public subnet. The web application has not been able to meet the demand of the increased web traffic.

The company needs a solution that will provide high availability and scalability to meet the increased user demand without rewriting the web application.

Which combination of steps will meet these requirements? (Choose two.)

Answer options

• A. Replace the EC2 instance with a larger compute optimized instance.
• B. Configure Amazon EC2 Auto Scaling with multiple Availability Zones in private subnets.
• C. Configure a NAT gateway in a public subnet to handle web requests.
• D. Replace the EC2 instance with a larger memory optimized instance.
• E. Configure an Application Load Balancer in a public subnet to distribute web traffic.

Correct answer: B, E

Explanation

To achieve high availability and scalability without modifying the application code, horizontal scaling is necessary. Configuring Amazon EC2 Auto Scaling across multiple Availability Zones (B) allows the application to dynamically scale out based on demand and survive zonal failures, while deploying an Application Load Balancer (E) distributes incoming web traffic evenly across those instances. Upgrading to larger instances (A and D) only scales vertically and fails to provide high availability, and a NAT gateway (C) is designed for outbound internet access from private subnets rather than handling incoming web traffic.