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CV0-004 Practice Question: A cloud administrator is debugging a failed…

Network Topology
$ aws cloudformation describe-stack-eventsstack-name WebAppRefer to the exhibit.```"StackEvents": ["StackId": "arn:aws:cloudformation:us-east-1:123456789012:stack/WebApp/...","EventId": "Event-1","StackName": "WebApp","LogicalResourceId": "WebApp","PhysicalResourceId": "arn:aws:cloudformation:us-east-1:123456789012:stack/WebApp/...","ResourceType": "AWS::CloudFormation::Stack","Timestamp": "2023-03-01T12:00:00.000Z","ResourceStatus": "CREATE_IN_PROGRESS","ResourceProperties": "..."},"LogicalResourceId": "WebServerInstance","ResourceType": "AWS::EC2::Instance","ResourceStatus": "CREATE_FAILED",Status Code: 400Error Code: InvalidGroup.NotFound)","Timestamp": "2023-03-01T12:05:00.000Z"

A cloud administrator is debugging a failed CloudFormation stack creation. The exhibit shows the stack events. What is the most likely cause of the failure?

⚠ Common exam trap

CompTIA often tests the ability to read CloudFormation stack events and correlate the failing resource with the specific error message, rather than assuming a generic failure like an incorrect AMI or instance type.

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 referenced security group does not exist in the chosen VPC.

The stack creation fails with a 'CREATE_FAILED' status on the security group resource, and the error message indicates that the security group does not exist in the specified VPC. This is a common issue when a CloudFormation template references a security group by ID or name that is not present in the target VPC, causing the resource creation to fail. The stack events show the security group resource as the point of failure, confirming that the referenced security group is missing.

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 instance type is not supported in the region.

    Why it's wrong here

    No error about instance type.

  • The stack name already exists.

    Why it's wrong here

    Stack creation in progress, not duplicate.

  • The AMI ID is incorrect.

    Why it's wrong here

    No AMI error.

  • The referenced security group does not exist in the chosen VPC.

    Why this is correct

    The error explicitly mentions invalid groupId.

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JA

Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

This CV0-004 practice question is part of Courseiva's free CompTIA 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 CV0-004 exam.