AWS Certified Solutions Architect – Associate (SAA-C03) — Question 444

A company has hired a solutions architect to design a reliable architecture for its application. The application consists of one Amazon RDS DB instance and two manually provisioned Amazon EC2 instances that run web servers. The EC2 instances are located in a single Availability Zone.

An employee recently deleted the DB instance, and the application was unavailable for 24 hours as a result. The company is concerned with the overall reliability of its environment.

What should the solutions architect do to maximize reliability of the application's infrastructure?

Answer options

• A. Delete one EC2 instance and enable termination protection on the other EC2 instance. Update the DB instance to be Multi-AZ, and enable deletion protection.
• B. Update the DB instance to be Multi-AZ, and enable deletion protection. Place the EC2 instances behind an Application Load Balancer, and run them in an EC2 Auto Scaling group across multiple Availability Zones.
• C. Create an additional DB instance along with an Amazon API Gateway and an AWS Lambda function. Configure the application to invoke the Lambda function through API Gateway. Have the Lambda function write the data to the two DB instances.
• D. Place the EC2 instances in an EC2 Auto Scaling group that has multiple subnets located in multiple Availability Zones. Use Spot Instances instead of On-Demand Instances. Set up Amazon CloudWatch alarms to monitor the health of the instances Update the DB instance to be Multi-AZ, and enable deletion protection.

Correct answer: B

Explanation

Option B is correct because enabling Multi-AZ deployment for Amazon RDS provides high availability, while enabling deletion protection prevents accidental administrative removal. Additionally, deploying the EC2 web servers inside an Auto Scaling group across multiple Availability Zones behind an Application Load Balancer ensures the compute layer is highly available and resilient to zone failures. Other options either reduce compute capacity (Option A), introduce unnecessary architecture complexity (Option C), or risk service disruption by using Spot Instances for a production web server layer (Option D).