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SAA-C03 · Question #151

A company has a website that handles dynamic traffic loads. The website architecture is based on Amazon EC2 instances in an Auto Scaling group that is configured to use scheduled scaling. Each EC2…

The correct answer is C. Target tracking scaling policy: Adjusts capacity based on actual demand, optimizing costs. The company needs to optimize costs for a website with dynamic traffic loads currently using scheduled scaling, while maintaining shared data storage on EFS.

Submitted by priya_blr· Mar 4, 2026Design Cost-Optimized Architectures

Question

A company has a website that handles dynamic traffic loads. The website architecture is based on Amazon EC2 instances in an Auto Scaling group that is configured to use scheduled scaling. Each EC2 instance runs code from an Amazon Elastic File System (Amazon EFS) volume and stores shared data back to the same volume. The company wants to optimize costs for the website. Which solution will meet this requirement?

Options

  • AFixed desired instances: Does not adapt to traffic load fluctuations, leading to inefficiencies.
  • BLarger EC2 instances: Increases costs unnecessarily.
  • CTarget tracking scaling policy: Adjusts capacity based on actual demand, optimizing costs.
  • DInstance store volumes: Not persistent and unsuitable for shared data across instances.

How the community answered

(50 responses)
  • A
    2% (1)
  • B
    4% (2)
  • C
    84% (42)
  • D
    10% (5)

Why each option

The company needs to optimize costs for a website with dynamic traffic loads currently using scheduled scaling, while maintaining shared data storage on EFS.

AFixed desired instances: Does not adapt to traffic load fluctuations, leading to inefficiencies.

Using a fixed desired number of instances does not adapt to dynamic traffic loads, leading to either over-provisioning (wasted costs) or under-provisioning (poor performance).

BLarger EC2 instances: Increases costs unnecessarily.
CTarget tracking scaling policy: Adjusts capacity based on actual demand, optimizing costs.Correct

A target tracking scaling policy for an Auto Scaling group automatically adjusts the number of EC2 instances based on actual demand metrics, such as CPU utilization, to maintain a target value. This reactive approach dynamically matches capacity to load, preventing over-provisioning and optimizing costs more effectively than scheduled scaling for dynamic workloads.

DInstance store volumes: Not persistent and unsuitable for shared data across instances.

Concept tested: Auto Scaling policies, cost optimization for dynamic workloads

Source: https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-scaling-target-tracking.html

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