AWS Certified Solutions Architect – Professional — Question 1013

A company runs a legacy system on a single m4.2xlarge Amazon EC2 instance with Amazon EBS storage. The EC2 instance runs both the web server and a self- managed Oracle database. A snapshot is made of the EBS volume every 12 hours, and an AMI was created from the fully configured EC2 instance.
A recent event that terminated the EC2 instance led to several hours of downtime. The application was successfully launched from the AMI, but the age of the
EBS snapshot and the repair of the database resulted in the loss of 8 hours of data. The system was also down for 4 hours while the Systems Operators manually performed these processes.
What architectural changes will minimize downtime and reduce the chance of lost data?

Answer options

• A. Create an Amazon CloudWatch alarm to automatically recover the instance. Create a script that will check and repair the database upon reboot. Subscribe the Operations team to the Amazon SNS message generated by the CloudWatch alarm.
• B. Run the application on m4.xlarge EC2 instances behind an Elastic Load Balancer/Application Load Balancer. Run the EC2 instances in an Auto Scaling group across multiple Availability Zones with a minimum instance count of two. Migrate the database to an Amazon RDS Oracle Multi-AZ DB instance.
• C. Run the application on m4.2xlarge EC2 instances behind an Elastic Load Balancer/Application Load Balancer. Run the EC2 instances in an Auto Scaling group across multiple Availability Zones with a minimum instance count of one. Migrate the database to an Amazon RDS Oracle Multi-AZ DB instance.
• D. Increase the web server instance count to two m4.xlarge instances and use Amazon Route 53 round-robin load balancing to spread the load. Enable Route 53 health checks on the web servers. Migrate the database to an Amazon RDS Oracle Multi-AZ DB instance.

Correct answer: B

Explanation

Migrating the self-managed database to an Amazon RDS Oracle Multi-AZ DB instance ensures high availability, synchronous replication, and automated failover, which minimizes data loss and database recovery time. Distributing the application layer across multiple Availability Zones using an Auto Scaling group with a minimum size of two behind an Application Load Balancer eliminates single points of failure for the web tier. Option C is incorrect because a minimum size of one still risks downtime if that single instance fails, while Option D lacks proper dynamic load balancing and autoscaling.