AWS Certified DevOps Engineer – Professional — Question 118

A company runs a three-tier web application in its production environment, which is built on a single AWS CloudFormation template made up of Amazon EC2 instances behind an ELB Application Load Balancer. The instances run in an EC2 Auto Scaling group across multiple Availability Zones. Data is stored in an Amazon RDS Multi-AZ DB instance with read replicas. Amazon Route 53 manages the application's public DNS record.

A DevOps engineer must create a workflow to mitigate a failed software deployment by rolling back changes in the production environment when a software cutover occurs for new application software.

What steps should the engineer perform to meet these requirements with the LEAST amount of downtime?

Answer options

• A. Use CloudFormation to deploy an additional staging environment and configure the Route 53 DNS with weighted records. During cutover change the Route 53 A record weights to achieve an even traffic distribution between the two environments. Validate the traffic in the new environment and immediately terminate the old environment if tests are successful.
• B. Use a single AWS Elastic Beanstalk environment to deploy the staging and production environments. Update the environment by uploading the ZIP file with the new application code. Swap the Elastic Beanstalk environment CNAME. Validate the traffic in the new environment and immediately terminate the old environment if tests are successful.
• C. Use a single AWS Elastic Beanstalk environment and an AWS OpsWorks environment to deploy the staging and production environments. Update the environment by uploading the ZIP file with the new application code into the Elastic Beanstalk environment deployed with the OpsWorks stack. Validate the traffic in the new environment and immediately terminate the old environment if tests are successful.
• D. Use AWS CloudFormation to deploy an additional staging environment, and configure the Route 53 DNS with weighted records. During cutover, increase the weight distribution to have more traffic directed to the new staging environment as workloads are successfully validated. Keep the old production environment in place until the new staging environment handles all traffic.

Correct answer: D

Explanation

The correct answer is D because it allows for a gradual transition by adjusting traffic weights, minimizing downtime while ensuring that the new environment is stable before fully switching over. Option A suggests terminating the old environment immediately after validation, which could risk downtime if issues arise. Options B and C do not utilize the weighted routing capabilities of Route 53, which are essential for a smooth cutover.