SOA-C02 Cost and Performance Optimization Practice Question
A SysOps team is using CloudWatch to monitor CPU utilization of EC2 instances. They want to receive a notification when average CPU exceeds 80% for 5 consecutive minutes. Which combination of services should they use?
⚠ Common exam trap
It's easy for candidates to confuse CloudWatch Logs with CloudWatch Metrics, assuming logs can be used for metric-based alarms, or they overcomplicate the solution by adding Lambda when SNS alone is sufficient for notification.
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
✓
CloudWatch Metrics, CloudWatch Alarm, and Amazon SNS
CloudWatch Metrics collects the CPU utilization data from EC2 instances, a CloudWatch Alarm evaluates whether the average CPU exceeds 80% for 5 consecutive minutes (using a period of 300 seconds and 5 datapoints), and Amazon SNS publishes the notification to subscribers (e.g., email, SMS) when the alarm state transitions to ALARM. This combination directly fulfills the requirement without unnecessary services.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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CloudWatch Metrics, CloudWatch Alarm, and AWS Lambda
Why it's wrong here
CloudWatch Alarms can directly publish notifications to Amazon SNS, rendering AWS Lambda superfluous for merely receiving an alert when the CPU threshold is breached. Lambda is not required to satisfy the notification requirement in this scenario. This option is tempting because Lambda is frequently integrated with CloudWatch Alarms to perform custom, programmatic actions, such as automatically stopping an EC2 instance or triggering a complex workflow, rather than just sending a simple message.
- ✗
AWS Config, CloudWatch Alarm, and Amazon SNS
Why it's wrong here
AWS Config is a service for recording configuration items, resource changes, and compliance against rules, not for ingesting or exposing infrastructure performance metrics. CPU utilization is published as a metric in the AWS/EC2 namespace, so AWS Config cannot supply the data an alarm would evaluate. Consequently, combining AWS Config, a CloudWatch Alarm, and SNS does not create a valid CPU alerting pipeline.
- ✓
CloudWatch Metrics, CloudWatch Alarm, and Amazon SNS
Why this is correct
Amazon EC2 automatically publishes CPUUtilization to the AWS/EC2 namespace in CloudWatch Metrics, providing the data source for evaluation. A CloudWatch Alarm continuously compares the metric against a threshold over a specified period and transitions between OK, ALARM, and INSUFFICIENT_DATA states. When the alarm enters ALARM, it invokes an action that publishes a message to an Amazon SNS topic, which then delivers notifications through endpoints such as email, SMS, or HTTP. This is the standard, minimal pattern for metric-based alerting.
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CloudWatch Logs, CloudWatch Alarm, and AWS Lambda
Why it's wrong here
CloudWatch Logs is designed to store and query log records from applications and the OS, but standard EC2 CPU utilization does not appear there unless you install an agent and create custom log streams; the native CPUUtilization metric lives only in CloudWatch Metrics. Even if a metric existed via a log filter, routing the alarm to AWS Lambda instead of directly to SNS adds needless complexity and latency for a plain notification, since CloudWatch Alarms can invoke SNS topics natively. The absence of an SNS topic in this option also leaves no clear delivery channel for the alert.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SOA-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 SOA-C02 exam.