SOA-C02 Monitoring, Logging, and Remediation Practice Question
A SysOps administrator notices that an EC2 instance's CPU utilization has been above 90% for the past hour. The instance is part of an Auto Scaling group with a CPU utilization-based scaling policy. However, no new instances have been launched. What is the most likely cause?
⚠ Common exam trap
A common mix-up: candidates assume high CPU utilization always triggers immediate scaling, overlooking the cooldown period that can delay or block subsequent scaling activities even when alarms are in ALARM state.
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
✓
The Auto Scaling cooldown period is preventing additional scaling activities.
The most likely cause is that the Auto Scaling cooldown period is preventing additional scaling activities. When a scaling activity completes, a cooldown period (default 300 seconds) starts during which the Auto Scaling group ignores additional CloudWatch alarms to allow metrics to stabilize. If the instance has been above 90% CPU for an hour but no new instances launched, the cooldown period may have been triggered by a previous scaling event and is still active, blocking further scale-out actions despite sustained high utilization.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The Auto Scaling cooldown period is preventing additional scaling activities.
Why this is correct
The Auto Scaling cooldown period is a configurable duration that begins after the most recent scaling activity completes. During this cooldown, the Auto Scaling group intentionally ignores new CloudWatch alarm triggers to prevent flapping, so even sustained high CPU will not launch additional instances until the cooldown expires. This is a common and often overlooked reason why a CPU-based alarm appears to have no effect.
- ✗
The EC2 instance is in a private subnet and cannot communicate with the Auto Scaling service.
Why it's wrong here
An Auto Scaling group does not rely on the EC2 instance to communicate with the Auto Scaling service; scaling decisions are driven by CloudWatch metrics and health check signals. Instances in a private subnet still send CPU metrics via the CloudWatch agent or are covered by hypervisor-level EC2 metrics, and the Auto Scaling service can act on those without direct internet access from the instance. Therefore, a private subnet would not block scaling activities.
- ✗
The CloudWatch alarm is publishing to an S3 bucket that is full.
Why it's wrong here
CloudWatch alarms do not publish to S3; they are resources that evaluate metric conditions and transition states, and in doing so they trigger actions such as Auto Scaling policies or SNS notifications. An S3 bucket being full has no effect on alarm evaluation or trigger delivery because CloudWatch's alarm state machine runs internally, not through object storage. This option is factually impossible and cannot be the cause.
- ✗
The scaling policy is based on memory utilization, not CPU.
Why it's wrong here
The question explicitly states the scaling policy is based on CPU utilization, so this policy is designed to react to CPU metrics, not memory. Even if another memory-based policy existed, that policy would be separate and irrelevant to the stated CPU-based scaling trigger. Thus, this option contradicts the premise and cannot explain why the CPU-driven scaling did not occur.
Go deeper
Related to this question
About these practice questions
One of 1,169 original SOA-C02 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
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.