Cost Optimization Improvement Strategy — AWS Solutions Architect Pro (SAP-C02)
Three Waste Signals, Three Different Fixes
SAP-C02 cost optimization questions embed the correct answer in the waste description. 'Idle resources during off-hours' points to scheduled scaling or EventBridge-triggered Lambda to stop instances outside business hours. 'Over-provisioned instances at 15 percent CPU' points to Compute Optimizer analysis followed by a resize. 'Predictable baseline with unpredictable spikes' points to a floor-and-ceiling split: Savings Plans cover the predictable baseline; Spot Instances or Lambda handle demand above it. Applying Reserved Instances to the entire fleet answers only the baseline portion correctly. Identify which portion of demand justifies commitment pricing and which requires elastic or interruptible compute before selecting a savings instrument.
What This Pattern Tests
The exam presents a running environment and tests ongoing cost optimization. AWS Cost Explorer shows spend trends and forecasts. Trusted Advisor flags idle resources (unattached EBS volumes at $0.10/GB/month, idle RDS instances, underutilized EC2). Cost Anomaly Detection alerts on unexpected spend spikes. Compute Optimizer recommends instance rightsizing. The trap is treating cost optimization as a one-time exercise — the exam tests whether your answer includes continuous monitoring, not just a one-time review. Savings Plans and Reserved Instances are the last step, after eliminating waste and rightsizing.
Decision Axis
Optimization sequence: eliminate waste first, rightsize second, optimize pricing third. Continuous monitoring, not one-time review.
Associated Traps
More Top Traps on This Exam
Decision Rules
Whether to commit reserved or Savings Plans capacity at Q4 peak instance count—maximizing the per-unit discount rate but stranding committed spend during 42 off-peak weeks—or to commit Compute Savings Plans only at the Compute Optimizer-validated steady-state baseline and absorb seasonal burst with Spot, achieving the required 35% blended savings rate without idle-capacity lock-in.
Domain Coverage
Difficulty Breakdown