A service that automatically adjusts resource capacity (EC2, ECS, DynamoDB) based on defined policies. It maintains availability and optimizes cost by scaling up under demand and scaling down when idle.
The elasticity mechanism on CLF-C02 and SAA-C03. It is configured with minimum, desired, and maximum instance counts. Policies: Target Tracking (keep CPU at 50%), Step Scaling, Scheduled. Question: what guarantees at least 2 instances are always running? An Auto Scaling Group with min=2.
AWS Auto Scaling is a concept that can show up on the exam. Check the full guide to see it in context.