- A
Add a step in the CodeBuild buildspec that runs 'aws ecs register-task-definition --cli-input-json file://taskdef.json --no-cli-pager --dry-run' to validate the task definition.
Why wrong: The 'aws ecs register-task-definition' command does not support the '--dry-run' flag; it would actually register the task definition. This option does not provide a validation-only mechanism.
- B
Add a step in the CodeBuild buildspec that runs 'aws ecs update-service --service my-service --task-definition <task-def-arn>' to see if the service accepts the task definition.
Correct. Attempting to update the service with the new task definition validates the definition, as the service will check for missing parameters and reject the update if invalid. It is a fast API call without side effects if the update is not applied (the pipeline can be configured to rollback).
- C
Add a step in the CodeBuild buildspec that runs 'aws ecs run-task --task-definition <task-def-arn> --count 1' to test the task definition.
Why wrong: Running a task with 'run-task' will incur costs and take time to start. While it can validate the task definition at runtime, it is less efficient than a simple API validation.
- D
Add a step in the CodeBuild buildspec that runs 'aws ecs describe-task-definition --task-definition <task-def-arn>' to check if the task definition exists.
Why wrong: The 'describe-task-definition' command only retrieves details of an existing task definition; it cannot validate a new, unregistered task definition.
DVA-C02 Deployment Practice Question
This DVA-C02 practice question tests your understanding of deployment. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 company is deploying a containerized application on Amazon ECS using Fargate launch type. The application consists of multiple microservices, each deployed as a separate ECS service. The company uses AWS CodePipeline to automate deployments. The pipeline has a Source stage (CodeCommit), a Build stage (CodeBuild), and a Deploy stage (ECS). Recently, a deployment failed because the new task definition referenced an environment variable that was not available in the Parameter Store. The developer wants to prevent such failures in the future by validating the task definition before deployment. The developer has access to the AWS CLI and the AWS SDKs. The pipeline is configured to use CodeBuild for the build stage. What is the MOST efficient way to validate the task definition before deployment?
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
Add a step in the CodeBuild buildspec that runs 'aws ecs update-service --service my-service --task-definition <task-def-arn>' to see if the service accepts the task definition.
Option B is the most efficient way to validate the task definition before deployment because 'aws ecs update-service' will attempt to update the service with the new task definition. If the task definition has missing or invalid references (e.g., environment variables not in Parameter Store), the API will return an error, allowing the pipeline to fail early. This avoids the cost and time of running a task (Option C) and does not require the task definition to already exist (Option D). Option A is invalid because the '--dry-run' flag is not supported by 'aws ecs register-task-definition'.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Add a step in the CodeBuild buildspec that runs 'aws ecs register-task-definition --cli-input-json file://taskdef.json --no-cli-pager --dry-run' to validate the task definition.
Why it's wrong here
The 'aws ecs register-task-definition' command does not support the '--dry-run' flag; it would actually register the task definition. This option does not provide a validation-only mechanism.
- ✓
Add a step in the CodeBuild buildspec that runs 'aws ecs update-service --service my-service --task-definition <task-def-arn>' to see if the service accepts the task definition.
Why this is correct
Correct. Attempting to update the service with the new task definition validates the definition, as the service will check for missing parameters and reject the update if invalid. It is a fast API call without side effects if the update is not applied (the pipeline can be configured to rollback).
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Add a step in the CodeBuild buildspec that runs 'aws ecs run-task --task-definition <task-def-arn> --count 1' to test the task definition.
Why it's wrong here
Running a task with 'run-task' will incur costs and take time to start. While it can validate the task definition at runtime, it is less efficient than a simple API validation.
- ✗
Add a step in the CodeBuild buildspec that runs 'aws ecs describe-task-definition --task-definition <task-def-arn>' to check if the task definition exists.
Why it's wrong here
The 'describe-task-definition' command only retrieves details of an existing task definition; it cannot validate a new, unregistered task definition.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Trap categories for this question
Command / output trap
The 'aws ecs register-task-definition' command does not support the '--dry-run' flag; it would actually register the task definition. This option does not provide a validation-only mechanism.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which DVA-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Deployment — This question tests Deployment — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a step in the CodeBuild buildspec that runs 'aws ecs update-service --service my-service --task-definition <task-def-arn>' to see if the service accepts the task definition. — Option B is the most efficient way to validate the task definition before deployment because 'aws ecs update-service' will attempt to update the service with the new task definition. If the task definition has missing or invalid references (e.g., environment variables not in Parameter Store), the API will return an error, allowing the pipeline to fail early. This avoids the cost and time of running a task (Option C) and does not require the task definition to already exist (Option D). Option A is invalid because the '--dry-run' flag is not supported by 'aws ecs register-task-definition'.
What should I do if I get this DVA-C02 question wrong?
Identify which DVA-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 20, 2026
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