The answer is that the EC2 instances do not have the tag 'Environment' with value 'Production'. This is correct because the CodeDeploy deployment group is explicitly configured to filter instances using that exact tag key-value pair; when CodeDeploy searches for target instances during a deployment, a tag mismatch means it cannot locate any matching hosts, resulting in the "instances not found" error. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how deployment groups rely on tag-based instance selection, a common trap being to overlook that the tag must match both the key and the value exactly—not just the key. A helpful memory tip is "Tag or Trag": if the tag doesn't match, your deployment is a tragedy.
DOP-C02 SDLC Automation Practice Question
This DOP-C02 practice question tests your understanding of sdlc automation. 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.
Network Topology
A CodeDeploy deployment group is configured as shown in the exhibit. During a deployment, the deployment fails because the instances are not found. What is the MOST likely reason?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The EC2 instances do not have the tag 'Environment' with value 'Production'
Option B is correct because the exhibit shows the deployment group is configured to match EC2 instances with the tag 'Environment' set to 'Production'. If the instances do not have this exact tag key-value pair, CodeDeploy cannot find them during the deployment, causing the failure. The error 'instances are not found' directly points to a tag mismatch, not to permissions or load balancer issues.
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.
✗
The deployment configuration 'CodeDeployDefault.AllAtOnce' is not compatible with in-place deployments
Why it's wrong here
AllAtOnce is a valid configuration for in-place deployments.
✓
The EC2 instances do not have the tag 'Environment' with value 'Production'
Why this is correct
The deployment group filters instances by tag; if no instances match, the deployment fails.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The service role ARN is incorrect and does not have the necessary permissions
Why it's wrong here
The role is specified; permission issues would cause a different error.
✗
The load balancer 'my-alb' is not registered with the instances
Why it's wrong here
The ALB is for traffic control; its registration status does not affect instance discovery.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'instances not found' errors with permission or load balancer issues, but the error is a direct result of tag mismatch, which is the most common cause in CodeDeploy tag-based deployments.
Detailed technical explanation
How to think about this question
CodeDeploy uses tag-based filtering to identify target instances for a deployment group. The deployment group configuration specifies key-value tag pairs, and CodeDeploy performs an EC2 DescribeInstances API call with those tags as filters. If no instances match the filter, the deployment fails with 'instances not found' before any deployment lifecycle events begin. This tag-based selection is independent of IAM permissions or load balancer associations, as those are validated at different stages.
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.
TExam Day Tips
→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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
SDLC Automation — This question tests SDLC Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The EC2 instances do not have the tag 'Environment' with value 'Production' — Option B is correct because the exhibit shows the deployment group is configured to match EC2 instances with the tag 'Environment' set to 'Production'. If the instances do not have this exact tag key-value pair, CodeDeploy cannot find them during the deployment, causing the failure. The error 'instances are not found' directly points to a tag mismatch, not to permissions or load balancer issues.
What should I do if I get this DOP-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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