SOA-C02 Deployment, Provisioning, and Automation Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Use a CloudFormation dynamic reference to the parameter store in the template.

  Why this is correct

  A dynamic reference using {{resolve:ssm:parameter-name}} is resolved by CloudFormation at the time a stack operation is performed, not when the template is authored. This means that when you update the stack after the Systems Manager Parameter Store value changes, CloudFormation automatically retrieves the current AMI ID and uses it for resource creation or replacement. It is the only option that inherently satisfies the requirement to automatically adopt the latest AMI ID without editing the template or providing manual input.

• ✗

  Use a CloudFormation mapping to map the AMI ID.

  Why it's wrong here

  A mapping stores key-value pairs as static literals inside the CloudFormation template itself. Although you can select an AMI ID based on a key such as an AWS region or environment, the mapping values are fixed at template authoring time; they cannot call the Systems Manager Parameter Store or read a live parameter value. To use a new AMI ID, you would have to edit the mapping in the template and perform a stack update, which does not meet the 'automatically uses the latest' requirement.

• ✗

  Use a custom resource to call Systems Manager to retrieve the AMI ID.

  Why it's wrong here

  Using a custom resource to fetch the AMI ID is insufficient because it typically executes only when the custom resource itself is created, updated, or replaced. A change to the Parameter Store value alone would not automatically trigger the custom resource to re-evaluate and provide the new AMI ID during a subsequent stack update, failing the "automatically uses the latest" requirement. Custom resources are valuable for extending CloudFormation's functionality, such as integrating with unsupported services or performing complex logic and transformations during deployment where native capabilities are lacking.

• ✗

  Use a CloudFormation parameter with a default value that matches the AMI ID.

  Why it's wrong here

  A parameter with a default value is baked into the template, and CloudFormation treats that default as a fixed value unless a different value is supplied at stack creation or update time. Changing the default in the template does not affect an existing stack until you explicitly update the stack with the new parameter value. Because the Parameter Store value is never consulted, the stack will continue using the old AMI ID even after the parameter changes.

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