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 CloudFormation stack creation failed as shown in the exhibit. What is the MOST likely cause of the failure?
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.
The subnet resource depends on a resource that was not created successfully
The subnet likely depends on the VPC, but the VPC succeeded; the error suggests the subnet's physical ID was not assigned, possibly due to a missing dependency or invalid property.
B
The VPC creation failed, so the subnet could not be created
Why wrong: The VPC was created successfully (CREATE_COMPLETE).
C
The CloudFormation service role does not have permission to create subnets
Why wrong: The error message does not indicate a permission issue; it says the subnet ID does not exist.
D
The subnet logical ID conflicts with an existing resource in the stack
Why wrong: There is no conflict; the error indicates the physical resource ID does not exist.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The subnet resource depends on a resource that was not created successfully
The exhibit shows that the VPC was created successfully, but the subnet creation failed with a 'dependency violation' error. In CloudFormation, when a resource depends on another resource that was not created successfully (or was deleted), the dependent resource cannot be created because the target resource (the VPC) no longer exists or is in a failed state. This is the most likely cause because the subnet depends on the VPC, and if the VPC was rolled back or deleted due to a prior failure, the subnet creation will fail with a dependency violation.
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 subnet resource depends on a resource that was not created successfully
Why this is correct
The subnet likely depends on the VPC, but the VPC succeeded; the error suggests the subnet's physical ID was not assigned, possibly due to a missing dependency or invalid property.
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 VPC creation failed, so the subnet could not be created
Why it's wrong here
The VPC was created successfully (CREATE_COMPLETE).
✗
The CloudFormation service role does not have permission to create subnets
Why it's wrong here
The error message does not indicate a permission issue; it says the subnet ID does not exist.
✗
The subnet logical ID conflicts with an existing resource in the stack
Why it's wrong here
There is no conflict; the error indicates the physical resource ID does not exist.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the subnet failed because the VPC creation failed, but the exhibit clearly shows the VPC succeeded, so the real issue is a dependency violation caused by the VPC being deleted or rolled back after initial creation.
Detailed technical explanation
How to think about this question
CloudFormation uses resource dependencies to determine the order of creation and deletion. When a resource depends on another (e.g., a subnet depends on a VPC), CloudFormation creates the dependency first. If the dependency fails or is deleted during a rollback, the dependent resource cannot be created because the underlying infrastructure (the VPC ID) is missing. This is enforced by the AWS API, which returns a 'dependency violation' error when you try to create a subnet in a non-existent VPC. In real-world scenarios, this often happens when a stack update or rollback deletes a resource that other resources depend on, leading to cascading failures.
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 subnet resource depends on a resource that was not created successfully — The exhibit shows that the VPC was created successfully, but the subnet creation failed with a 'dependency violation' error. In CloudFormation, when a resource depends on another resource that was not created successfully (or was deleted), the dependent resource cannot be created because the target resource (the VPC) no longer exists or is in a failed state. This is the most likely cause because the subnet depends on the VPC, and if the VPC was rolled back or deleted due to a prior failure, the subnet creation will fail with a dependency violation.
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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