Examkin

Question

Difficulty: MediumAuto Scaling and Elasticity

A SysOps administrator is managing an Amazon EC2 Auto Scaling group (ASG) that uses a step scaling policy to scale out when average CPU utilization exceeds 70%70\%. During unexpected traffic spikes, the ASG launches new instances, but it continues to launch more instances every 22 minutes before the previously launched instances have finished bootstrapping and begun processing traffic. This behavior causes the group to scale out beyond the required capacity, leading to unnecessary costs. Which action will prevent the ASG from launching additional instances while the newly launched instances are still bootstrapping?

  1. Increase the estimated instance warmup time for the step scaling policy.Answer
  2. B
    Increase the default cooldown period in the Auto Scaling group configuration.
  3. C
    Enable detailed monitoring for the EC2 instances within the launch template.
  4. D
    Configure an Amazon EventBridge rule to trigger a Systems Manager Automation document that pauses scaling processes.

Answer

Increase the estimated instance warmup time for the step scaling policy.
Increasing the estimated instance warmup time ensures that newly launched instances are given sufficient time to complete bootstrapping and start handling traffic before their metrics are included in the Auto Scaling group's aggregate metrics. During this warmup period, the step scaling policy will not initiate further scale-out actions, preventing the group from over-provisioning resources during a spike.

Step-by-Step Solution

1
Identify the type of scaling policy in use by the Auto Scaling group.
The ASG is configured with a step scaling policy.
Different scaling policies use different mechanisms to handle the period immediately following an instance launch.
2
Determine how the step scaling policy handles new instance initialization.
Step scaling policies rely on the estimated instance warmup parameter, during which newly launched instances do not contribute to the ASG's aggregated metrics, and further scale-out events are paused.
Without a sufficient warmup period, the high average CPU utilization of existing instances will trigger subsequent scaling events before the new instances can start serving traffic.
3
Contrast the warmup parameter with the default cooldown period.
The default cooldown period only applies to simple scaling policies, meaning modifying it will not affect the step scaling policy's behavior.
This avoids misconfiguring the ASG by changing settings that have no effect on the current policy type.

Key Concept

Instance warmup in dynamic scaling policies
Rate this question

Topics

Auto Scaling and Elasticity

More questions from this topic