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Difficulty: MediumCloudWatch Metrics and Alarms

A SysOps Administrator is configuring an Amazon CloudWatch alarm to trigger a scale-out policy for an Auto Scaling group when the average CPU utilization exceeds 75%. The EC2 instances are launched using a template with default monitoring. The administrator sets the CloudWatch alarm period to 1 minute and the evaluation periods to 3. However, after a traffic spike, the scaling policy does not execute, and the CloudWatch alarm remains in the INSUFFICIENT_DATA state. Which action will resolve this issue and allow the alarm to transition to the ALARM state?

  1. Enable detailed monitoring in the launch template used by the Auto Scaling group.Answer
  2. B
    Reduce the Auto Scaling group cooldown period to 60 seconds to align with the alarm period.
  3. C
    Configure the alarm to use a high-resolution period of 10 seconds for the CPUUtilization metric.
  4. D
    Create an Amazon EventBridge rule that monitors the CPUUtilization metric and targets the scaling policy directly.

Answer

Enable detailed monitoring in the launch template used by the Auto Scaling group.
Enabling detailed monitoring in the launch template ensures that the EC2 instances publish metrics to CloudWatch every 1 minute instead of the default 5 minutes. This satisfies the alarm's configuration of a 1-minute period with 3 evaluation periods, allowing the alarm to retrieve enough data points to evaluate its state and trigger the scaling policy.

Step-by-Step Solution

1
Identify the cause of the INSUFFICIENT_DATA state.
By default, Amazon EC2 sends metrics to CloudWatch at 5-minute intervals (standard monitoring).
Since the alarm is configured with a 1-minute period and requires 3 consecutive evaluation periods, it expects three consecutive 1-minute data points. Under standard monitoring, data points are only available every 5 minutes, leaving gaps.
2
Modify the instance configuration to publish metrics at a higher frequency.
Enable detailed monitoring in the Auto Scaling group launch template.
Detailed monitoring publishes EC2 metrics to CloudWatch at 1-minute intervals, which ensures the alarm has continuous, consecutive 1-minute data points to evaluate.

Key Concept

CloudWatch Metric Granularity for EC2 Instances
Estimated Time:1m 30s
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Topics

CloudWatch Metrics and Alarms

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