AWS Certified Solutions Architect – Professional (SAP-C02) — Question 237

A company has a website that runs on four Amazon EC2 instances that are behind an Application Load Balancer (ALB). When the ALB detects that an EC2 instance is no longer available, an Amazon CloudWatch alarm enters the ALARM state. A member of the company's operations team then manually adds a new EC2 instance behind the ALB.

A solutions architect needs to design a highly available solution that automatically handles the replacement of EC2 instances. The company needs to minimize downtime during the switch to the new solution.

Which set of steps should the solutions architect take to meet these requirements?

Answer options

• A. Delete the existing ALB. Create an Auto Scaling group that is configured to handle the web application traffic. Attach a new launch template to the Auto Scaling group. Create a new ALB. Attach the Auto Scaling group to the new ALB. Attach the existing EC2 instances to the Auto Scaling group.
• B. Create an Auto Scaling group that is configured to handle the web application traffic. Attach a new launch template to the Auto Scaling group. Attach the Auto Scaling group to the existing ALAttach the existing EC2 instances to the Auto Scaling group.
• C. Delete the existing ALB and the EC2 instances. Create an Auto Scaling group that is configured to handle the web application traffic. Attach a new launch template to the Auto Scaling group. Create a new ALB. Attach the Auto Scaling group to the new ALB. Wait for the Auto Scaling group to launch the minimum number of EC2 instances.
• D. Create an Auto Scaling group that is configured to handle the web application traffic. Attach a new launch template to the Auto Scaling group. Attach the Auto Scaling group to the existing ALB. Wait for the existing ALB to register the existing EC2 instances with the Auto Scaling group.

Correct answer: B

Explanation

Option B is correct because it allows for the existing infrastructure to remain in place while integrating the Auto Scaling group, thereby minimizing downtime. The other options either involve deleting the current ALB or EC2 instances, which would lead to increased downtime during the transition, or do not effectively make use of the existing resources.