SOA-C03 practice question 1 of 10

Optimization] A CloudOps engineer is using AWS Compute Optimizer to generate recommendations for a fleet of Amazon EC2 instances. Some of the…

Domain Cost and Performance Optimization

Optimization] A CloudOps engineer is using AWS Compute Optimizer to generate recommendations for a fleet of Amazon EC2 instances. Some of the instances use newly released instance types, while other instances use older instance types. After the analysis is complete, the CloudOps engineer notices that some of the EC2 instances are missing from the Compute Optimizer dashboard. What is the likely cause of this issue?

Answer options

A: The missing instances have insufficient historical Amazon CloudWatch metric data for analysis.

B: Compute Optimizer does not support the instance types of the missing instances. Correct answer

C: Compute Optimizer already considers the missing instances to be optimized.

D: The missing instances are running a Windows operating system.

Correct Answer:

B. Compute Optimizer does not support the instance types of the missing instances.

Explanation

AWS Compute Optimizer generates recommendations only for a specific list of supported EC2 instance types. If an instance type is not on this list, Compute Optimizer will not process it, and consequently, it will not appear on the dashboard. The question highlights that the fleet includes "newly released instance types" and "older instance types," which are the most likely candidates to be unsupported. Newly released types may not have been added to the supported list yet, and very old types might be excluded. This makes an unsupported instance type the most probable reason for the instances being missing from the analysis.

Why Incorrect

A. An instance with insufficient data is typically listed in the dashboard with a finding status of "Insufficient data" or "Not yet analyzed," not completely missing.
C. Optimized instances are explicitly displayed on the dashboard with the finding status "Optimized." The service does not hide them.
D. AWS Compute Optimizer supports instances running both Windows and Linux operating systems. The OS is not a reason for an instance to be excluded from the dashboard.

References

1. AWS Compute Optimizer User Guide

"Supported resources and requirements": This section explicitly lists the EC2 instance types that are supported for analysis. It states

"Compute Optimizer generates recommendations for the following EC2 instance types." If an instance type is not on this list

it is not analyzed. (AWS Documentation)

2. AWS Compute Optimizer User Guide

"Troubleshooting": Under the topic "Why are some of my resources missing from the Compute Optimizer dashboard?"

the guide lists the primary reason as "The resource is not of a supported configuration." This directly corresponds to the instance type not being supported. (AWS Documentation)

3. AWS Compute Optimizer User Guide

"Getting started with AWS Compute Optimizer"

"Prerequisites": This section outlines the requirements for resources to be analyzed. It lists two key prerequisites for EC2 instances: "The instances must be of a supported instance type" and "The instances must have accumulated sufficient metric data in CloudWatch." The scenario's details about new and old instance types point specifically to the first prerequisite. (AWS Documentation)

Question breakdown

Tests: Troubleshoot AWS Compute Optimizer coverage for EC2 rightsizing
Difficulty: Medium

Key idea: Compute Optimizer analyzes only EC2 instances whose instance types are on its supported list, so unsupported types are left out of the results entirely.

How to reach the answer

The symptom is that instances are missing from the dashboard, not that they show a particular finding.
The question deliberately mentions both newly released and older instance types.
Compute Optimizer only analyzes a defined set of instance families, and that set can lag new launches or exclude legacy generations.
Optimized instances still appear with an Optimized finding, and Windows instances are supported, so neither explains the gap.
The instance-type clue therefore points to unsupported types.

Each option

AIncorrect. Metric history is a real requirement, but nothing in the scenario points to it; the question highlights instance-type age instead.
BCorrect. Instance types outside Compute Optimizer's supported list are not analyzed, so they do not show up in the recommendations.
CIncorrect. Instances that are already well sized are still listed, with a finding of Optimized.
DIncorrect. Compute Optimizer supports Windows instances, so the operating system does not remove them from the analysis.

Common trap: Option A is tempting because metric history is a genuine Compute Optimizer prerequisite, but the scenario's clue is about new and old instance types, not about how long instances have run.

In practice: During cost reviews, teams often find that legacy-generation or brand-new instance types are absent from Compute Optimizer exports and have to rightsize them manually or migrate them to supported families.

Remember: If EC2 instances are missing from Compute Optimizer, first check whether their instance types are supported.

Official documentation: AWS Compute Optimizer supported resources and requirements

Reviewed by David Mercer.

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