CloudWatch Alarm Duration Threshold for CPU
A DevOps engineer is setting up an alarm to notify the team when the average CPU utilization of an EC2 instance exceeds 80% for 5 consecutive minutes. Which CloudWatch alarm configuration should be used?
Quick Answer
The correct answer is a CloudWatch alarm configured with the CPUUtilization metric, the Average statistic, a Period of 300 seconds, a Threshold of 80, and Evaluation Periods set to 1. This works because the Period defines the window over which the metric is aggregated—300 seconds equals exactly 5 minutes—and a single evaluation period means the alarm triggers when that one 5-minute data point breaches the threshold, satisfying the requirement of “exceeds 80% for 5 consecutive minutes.” On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how Period and Evaluation Periods interact: many candidates mistakenly increase Evaluation Periods to 5, thinking they need five separate checks, but that would require the condition to hold for 25 minutes, not 5. The common trap is confusing “consecutive minutes” with “consecutive evaluation periods.” Memory tip: think of it as “one window, one check”—a single 300-second period is already the full 5-minute duration, so one evaluation period is all you need.
⚠ Common exam trap
Many candidates confuse 'Evaluation Periods' with 'Period' — candidates often think 5 evaluation periods with a 60-second period is needed for 5 consecutive minutes, but that actually requires 5 separate 1-minute data points all breaching the threshold, not a single 5-minute average.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Metric: CPUUtilization, Statistic: Average, Period: 300 seconds, Threshold: 80, Evaluation Periods: 1
It configures a CloudWatch alarm with a 300-second (5-minute) period and 1 evaluation period, meaning the alarm triggers when the average CPU utilization exceeds 80% for a single 5-minute data point. This directly matches the requirement of 'exceeds 80% for 5 consecutive minutes' since the metric is evaluated over a 5-minute window.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Metric: CPUUtilization, Statistic: Average, Period: 300 seconds, Threshold: 80, Evaluation Periods: 1
Why this is correct
This matches the requirement: 5 consecutive minutes = 1 evaluation period of 300 seconds.
- ✗
Metric: CPUUtilization, Statistic: Average, Period: 300 seconds, Threshold: 80, Evaluation Periods: 1, Comparison: LessThanThreshold
Why it's wrong here
Comparison should be GreaterThanThreshold.
- ✗
Metric: CPUUtilization, Statistic: Average, Period: 60 seconds, Threshold: 80, Evaluation Periods: 5
Why it's wrong here
Period should be 300 seconds, not 60.
- ✗
Metric: CPUUtilization, Statistic: Sum, Period: 60 seconds, Threshold: 80, Evaluation Periods: 5
Why it's wrong here
Sum is incorrect; Average is needed.
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Same concept, more angles
1 more way this is tested on DOP-C02
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Variation 1. A DevOps engineer needs to set up an alert for when the CPU utilization of an EC2 instance exceeds 90% for 5 consecutive minutes. Which CloudWatch features should be used?
easy- A.CloudWatch Logs with a metric filter on CPU utilization logs.
- B.CloudTrail to monitor EC2 instance CPU usage.
- ✓ C.CloudWatch alarm on the CPUUtilization metric with a period of 5 minutes and threshold of 90.
- D.Amazon S3 server access logs to check CPU utilization.
Why C: CloudWatch alarms can be configured on the `CPUUtilization` metric (a standard EC2 metric emitted every 5 minutes by default) with a threshold of 90 and an evaluation period of 1 (since the period is set to 5 minutes, one evaluation period covers the 5 consecutive minutes). This directly meets the requirement without additional setup.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DOP-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DOP-C02 exam.