Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A developer is using AWS CodeDeploy to deploy an application to an Amazon ECS service with the Fargate launch type. The deployment uses a blue/green strategy. After the new task set is created and passes the initial health checks, the traffic is shifted to the new task set. However, the new task set is immediately replaced by the old one after a few minutes, causing a rollback. What is the most likely reason?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
The lifecycle hooks for the new task set are failing.
Lifecycle hooks run before traffic is shifted; if they fail, the deployment would not proceed to traffic shift, so this does not match the described sequence.
B
Distractor review
The target group for the new task set is not configured correctly.
Incorrect target group configuration might cause traffic routing issues, but it would not directly trigger a rollback; the deployment would likely complete with routing errors.
C
Distractor review
The deployment group's rollback configuration triggers due to alarm threshold.
Rollback due to CloudWatch alarms is possible, but the scenario states the rollback happens 'after a few minutes' immediately after traffic shift, which is typical of post-traffic validation failure, not an alarm that takes time to evaluate.
D
Best answer
The new task set fails the post-traffic shift validation tests.
CodeDeploy performs validation after traffic shift; if the validation fails (e.g., health check failure or Lambda hook failure), it triggers an automatic rollback to the original task set.
Common exam trap
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.
Technical deep dive
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.
Related practice questions
Related DVA-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A developer is building a REST API using Amazon API Gateway that will serve static content from an Amazon S3 bucket. The API should cache responses for frequently accessed objects to reduce latency. Which API Gateway feature should the developer enable?
Question 2
A developer is running a web application on multiple Amazon EC2 instances behind an Application Load Balancer (ALB). The application needs to store user session state that must be available across all instances. The session data is small and temporary but must survive individual instance failures. Which AWS service should the developer use to store this session state?
Question 3
A developer has an AWS Lambda function that processes messages from an Amazon SQS standard queue. The function is idempotent and currently has a batch size of 10. The developer wants to increase throughput and increases the batch size to 100. After the change, CloudWatch metrics show a significant increase in throttles and the queue backlog is growing. The function's reserved concurrency is set to 10. What is the most effective action to resolve the throttling and improve throughput?
Question 4
A developer is managing an application running on Amazon EC2 instances behind an Application Load Balancer. Users report that the application becomes unresponsive after several hours, and restarting the instance temporarily fixes the issue. The developer suspects a memory leak but cannot add custom instrumentation. Which AWS service can collect memory utilization metrics and help identify the memory leak with minimal configuration?
Question 5
A developer is building a serverless web application using AWS Lambda and Amazon DynamoDB. The application needs to perform complex aggregations on data stored in DynamoDB. Which AWS service should the developer use to perform these aggregations efficiently without reading all the data into Lambda?
Question 6
A developer has an Amazon S3 bucket containing private user documents. The application must generate a time-limited URL for users to download their own documents without requiring the users to have AWS credentials. Which solution should the developer use?
FAQ
Questions learners often ask
What does this DVA-C02 question test?
Read the scenario before looking for a memorised answer.
What is the correct answer to this question?
The correct answer is: The new task set fails the post-traffic shift validation tests. — In a blue/green deployment with CodeDeploy for ECS, after traffic is shifted, CodeDeploy runs post-traffic shift validation hooks. If these hooks fail (e.g., a Lambda function returns a failure, or the target group health checks fail), CodeDeploy initiates a rollback to the original task set. Option A is incorrect because lifecycle hooks before traffic shift would prevent traffic from being shifted if they fail. Option B would affect traffic routing but not trigger an automatic rollback. Option C could cause rollback if alarms are configured, but the scenario specifies no alarms, and the rollback occurs shortly after traffic shift, aligning with validation failure.
What should I do if I get this DVA-C02 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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