AWS Certified Solutions Architect – Associate (SAA-C03)Design High-Performing ArchitecturesMedium
A web application experiences predictable daily traffic patterns, with peak usage occurring during business hours and significantly lower usage overnight. The application is hosted on Amazon EC2 instances. To optimize costs and maintain performance, the Solutions Architect wants to ensure that compute capacity scales up during peak times and scales down during off-peak hours automatically. Which EC2 Auto Scaling feature should be configured?
- AStep Scaling Policy
- BSimple Scaling Policy
- CScheduled Scaling Policy
- DTarget Tracking Scaling Policy
Show answer & explanationAnswer & explanation
Correct answer: C. Scheduled Scaling Policy
A Scheduled Scaling Policy allows you to define a schedule for scaling actions, specifying when to increase or decrease the number of instances. This is ideal for predictable traffic patterns like daily business hours and overnight lulls, enabling cost optimization by matching capacity to known demand.
Why the other options are wrong
- A. Step Scaling Policy adjusts capacity in steps based on the magnitude of the alarm breach, which is reactive and more complex than needed for predictable schedules.
- B. Simple Scaling Policy adjusts capacity in response to a single alarm threshold, also reactive and less precise for predictable schedules.
- D. Target Tracking Scaling Policy adjusts capacity to maintain a specified metric (e.g., CPU utilization) at a target value, which is reactive, not proactive for predictable patterns.
EC2 Auto Scaling Scheduled Scaling
An EC2 Auto Scaling policy type that allows you to configure capacity changes based on a predictable schedule.
- Ideal for known traffic patterns (e.g., daily, weekly).
- Proactively adjusts instance count before demand changes.
- Helps optimize costs by scaling down during off-peak periods.
- Can be combined with dynamic scaling policies for unexpected spikes.
Memory trick: Auto Scaling's brain, policies explain: Target's goal, Simple's call, Scheduled's time, Step's climb.