An EC2 web server has detailed monitoring enabled and reports CPUUtilization every minute, with no missing data.
Notify operators through an SNS topic with configured subscriptions when all five most recent one-minute averages exceed 80%.
Which configuration is most appropriate?
Evaluate Average CPUUtilization with Period=60 seconds, EvaluationPeriods=5, and DatapointsToAlarm=5, and configure an SNS action for ALARM. One five-minute average tests a different condition.
Detailed explanation
One five-minute average can breach even when an individual one-minute average does not. It does not test all five averages.
One five-minute average can breach even when an individual one-minute average does not. It does not test all five averages.
CloudTrail audits API activity; it does not evaluate the CPU utilization time series.
CloudTrail audits API activity; it does not evaluate the CPU utilization time series.
All five one-minute averages must breach. The ALARM state transition can notify the configured SNS topic.
All five one-minute averages must breach. The ALARM state transition can notify the configured SNS topic.
One breach among five datapoints can trigger this alarm, including a short-lived spike.
One breach among five datapoints can trigger this alarm, including a short-lived spike.
Check official documentation
Compare the following points with the official documentation.
Review CloudWatch alarm evaluation settings, EC2 detailed monitoring, and SNS alarm actions.
Official references
What to confirm
Distinguish 60-second 5/5 evaluation from a single five-minute average.
Key points
- CloudWatch alarm
- CPUUtilization
- Evaluation period
Notes
- Environment: AWS SOA-C03 exam guide and the linked AWS documentation
- Reviewed against the linked AWS documentation on 2026-10-03.
Foundation review
Period, N, and M
Period defines each aggregation interval; EvaluationPeriods=N defines the number evaluated; DatapointsToAlarm=M defines the required breaches. With no missing data, 60 seconds and 5/5 test all five recent one-minute averages.
Aggregation and delivery
Breaching one-minute averages does not guarantee that every second exceeds the threshold. Operator delivery also requires an SNS alarm action and configured subscriptions.