Question 16
Domain 3: Continuous Improvement for Existing SolutionsA company has deployed production workloads on Amazon EC2 On-Demand Instances and Amazon RDS for PostgreSQL DB instances in multiple environments. The company has the AWS Business Support plan. A solutions architect must optimize the cost of the workloads without negatively affecting the availability or compute capacity of the workloads. Which solution will meet these requirements?
Correct answer: C
Explanation
AWS Compute Optimizer is a “rightsizing visibility” tool, and Trusted Advisor helps identify “underutilized instances,” which supports cost reduction without reducing availability. Implementing recommendations, modifying instance types, and using Auto Scaling groups preserves compute capacity, while a Compute Savings Plan matches the “pricing models” guidance for lowering EC2 costs.
Why each option is right or wrong
A. Use AWS Cost and Usage Reports to analyze the most expensive instances and usage patterns. Use AWS Lambda to terminate underutilized instances. Purchase Compute Savings Plans for instances for highly utilized workloads.
Terminating instances reduces capacity; Savings Plans lower cost without stopping workloads.
B. Use AWS Budgets to track spending for each environment. Configure AWS Trusted Advisor cost optimization checks to rightsize instances. Create billing alerts in Amazon CloudWatch. Terminate underutilized instances. Purchase Reserved Instances for highly utilized workloads.
Budgets and CloudWatch alerts monitor spend; they do not rightsize or replace purchasing analysis.
C. Opt in to AWS Compute Optimizer. Use Compute Optimizer and AWS Trusted Advisor to identify underutilized instances. Implement recommendations from Compute Optimizer, modify instance types, rightsize instances, and apply Auto Scaling groups. Purchase a Compute Savings Plan.
AWS Compute Optimizer is the service that provides rightsizing recommendations for EC2 and RDS based on utilization metrics, and AWS Trusted Advisor’s underutilized-resource checks are available with the AWS Business Support plan. Under the EC2 On-Demand pricing model, moving to a Compute Savings Plan can reduce cost while preserving capacity commitments, and the recommendation to modify instance types and use Auto Scaling maintains availability rather than simply terminating capacity; this aligns with the cost-optimization guidance in AWS Well-Architected and the support-plan access to Trusted Advisor checks.
D. Use AWS Cost Explorer recommendations to rightsize underutilized instances. Create billing alerts in Amazon CloudWatch. Replace the EC2 On-Demand Instances with Spot Instances for underutilized instances. Stop any instances that are not in use.
Spot Instances suit interruptible workloads; stopping instances can negatively affect availability.