Quick Answer
The answer is the test listener and target group mapping in the CodeDeploy deployment group. In an ECS blue/green deployment with an Application Load Balancer, CodeDeploy orchestrates traffic shifting by using two distinct listener-target group pairs: the production listener routes traffic to the original task set, while the test listener is specifically configured to route test traffic to the replacement task set. If the replacement set never receives test traffic, the mapping between the test listener and its associated target group is almost certainly misconfigured or missing in the deployment group settings. On the AWS Certified Developer Associate DVA-C02 exam, this concept tests your understanding of how CodeDeploy manages lifecycle hooks and traffic routing during blue/green deployments—a common trap is confusing the test listener with the production listener or assuming the load balancer automatically handles test traffic. Remember the mnemonic: “Test traffic needs its own listener-target pair,” so always verify that the test listener is explicitly mapped to the replacement target group in the deployment group configuration.
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.
An ECS blue/green deployment with CodeDeploy and an Application Load Balancer fails because the replacement task set never receives test traffic. Which configuration should be checked?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "never"
Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
S3 bucket versioning
Why wrong: This does not meet the stated requirement as directly as the correct option.
Lambda provisioned concurrency
Why wrong: This does not meet the stated requirement as directly as the correct option.
The test listener and target group mapping in the deployment group
Correct for the stated requirement.
DynamoDB TTL
Why wrong: This does not meet the stated requirement as directly as the correct option.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The test listener and target group mapping in the deployment group
In an ECS blue/green deployment with CodeDeploy and an Application Load Balancer, the test listener and its associated target group are responsible for routing test traffic to the replacement task set. If the replacement task set never receives test traffic, the most likely cause is that the test listener is not correctly mapped to the target group in the CodeDeploy deployment group configuration. This mapping ensures that traffic from the test listener is directed to the replacement task set during the deployment lifecycle.
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.
S3 bucket versioning
Why it's wrong here
This does not meet the stated requirement as directly as the correct option.
Lambda provisioned concurrency
Why it's wrong here
This does not meet the stated requirement as directly as the correct option.
The test listener and target group mapping in the deployment group
Why this is correct
Correct for the stated requirement.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
DynamoDB TTL
Why it's wrong here
This does not meet the stated requirement as directly as the correct option.
Common exam traps
The trap here is that candidates may confuse the test listener with the production listener or assume the issue is with the ALB itself, rather than recognizing that the test listener-to-target-group mapping in the CodeDeploy deployment group is the specific configuration that controls test traffic routing.
Detailed technical explanation
Under the hood, CodeDeploy orchestrates blue/green deployments by creating a replacement task set and registering it with a target group. The test listener (often on a different port) is used to validate the replacement task set before shifting production traffic. If the test listener's target group is misconfigured or not associated with the replacement task set, the test traffic will not reach the new tasks, causing the deployment to fail. In real-world scenarios, this often happens when the deployment group's 'TestListenerArn' or 'TestTargetGroupArn' is missing or points to an incorrect resource.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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: The test listener and target group mapping in the deployment group — In an ECS blue/green deployment with CodeDeploy and an Application Load Balancer, the test listener and its associated target group are responsible for routing test traffic to the replacement task set. If the replacement task set never receives test traffic, the most likely cause is that the test listener is not correctly mapped to the target group in the CodeDeploy deployment group configuration. This mapping ensures that traffic from the test listener is directed to the replacement task set during the deployment lifecycle.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "never". Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 11, 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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