This DVA-C02 practice question tests your understanding of deployment. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A developer is using AWS CloudFormation to create a stack that includes an EC2 instance. The stack creation fails because the instance type is not supported in the selected Availability Zone. What should the developer do?
Delete the stack and start over.
Why wrong: Can update the stack.
Change the instance type to one that is supported.
Why wrong: Instance type may be required; better to fix AZ.
Update the stack to specify a different subnet or not specify an Availability Zone.
CloudFormation can choose an AZ automatically.
Create the stack in a different region.
Why wrong: Not necessary; fix AZ.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Update the stack to specify a different subnet or not specify an Availability Zone.
Option C is correct because when an EC2 instance type is not supported in a specific Availability Zone (AZ), the developer can update the CloudFormation stack to either specify a different subnet (which implicitly selects a different AZ) or omit the Availability Zone parameter entirely, allowing AWS to automatically choose an AZ where the instance type is supported. This avoids the need to delete the stack or change the instance type, preserving other stack resources and configurations.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Delete the stack and start over.
Why it's wrong here
Can update the stack.
Change the instance type to one that is supported.
Why it's wrong here
Instance type may be required; better to fix AZ.
Update the stack to specify a different subnet or not specify an Availability Zone.
Why this is correct
CloudFormation can choose an AZ automatically.
Related concept
Read the scenario before looking for a memorised answer.
Create the stack in a different region.
Why it's wrong here
Not necessary; fix AZ.
Common exam traps
The trap here is that candidates assume the only fix is to change the instance type (Option B) or restart from scratch (Option A), overlooking CloudFormation's ability to update the stack's subnet or AZ selection to match the instance type's availability.
Detailed technical explanation
Under the hood, CloudFormation's `AWS::EC2::Instance` resource allows you to specify an `AvailabilityZone` property or a `SubnetId` property (which implicitly determines the AZ). If you omit both, CloudFormation uses the default VPC and lets AWS select an AZ automatically, which often resolves unsupported instance type errors because AWS can choose an AZ with available capacity. In practice, this is common with newer or specialized instance types (e.g., `p3.8xlarge` for GPU workloads) that may only be available in certain AZs within a region.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
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FAQ
Deployment — This question tests Deployment — Read the scenario before looking for a memorised answer..
The correct answer is: Update the stack to specify a different subnet or not specify an Availability Zone. — Option C is correct because when an EC2 instance type is not supported in a specific Availability Zone (AZ), the developer can update the CloudFormation stack to either specify a different subnet (which implicitly selects a different AZ) or omit the Availability Zone parameter entirely, allowing AWS to automatically choose an AZ where the instance type is supported. This avoids the need to delete the stack or change the instance type, preserving other stack resources and configurations.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This DVA-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 DVA-C02 exam.
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