The correct answer is that an RDS instance with the same identifier already exists in the account and region. This error occurs because CloudFormation, during a stack update or creation, attempts to provision a resource with a logical ID and physical name, but finds a pre-existing RDS instance using that exact DB instance identifier. The core technical concept here is that CloudFormation does not automatically manage resources left behind from a previously deleted stack; if the stack was deleted without retaining the resource, the orphaned RDS instance remains, causing a naming conflict when a new stack tries to create one with the same identifier. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of resource lifecycle management and the importance of checking for orphaned resources before redeploying. A common trap is confusing this with deletion protection, which prevents deletion but does not cause a CREATE_FAILED error for a new stack. Memory tip: "Orphaned ID, stack won't hide" — always verify that no resource with the same identifier exists in the account and region before attempting a new CloudFormation deployment.
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.
A team uses AWS CloudFormation to manage infrastructure. They have a stack that creates an Amazon RDS instance. During an update, the stack fails with 'CREATE_FAILED' for the DB instance resource, and the error message indicates 'The DB instance already exists.' What is the most likely cause?
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
✓
An RDS instance with the same identifier already exists in the account and region.
Option B is correct because if the stack was previously deleted without retaining the resource, the DB instance may have been left behind. Option A is wrong because RDS does not have a deletion policy that prevents deletion. Option C is wrong because UpdateReplace policy would replace but not cause 'already exists' error. Option D is wrong because deletion protection would prevent deletion but not cause 'already exists' if the stack is new.
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.
✓
An RDS instance with the same identifier already exists in the account and region.
Why this is correct
DB instance identifiers must be unique per region; if one exists, creation 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 stack update is trying to replace the DB instance without a proper UpdateReplace policy.
Why it's wrong here
UpdateReplace policy affects replacement behavior, but the error is about creation.
✗
The stack has a DeletionPolicy of Retain on the RDS instance.
Why it's wrong here
Retain would keep the instance after stack deletion, but the error occurs during creation, not after deletion.
✗
The RDS instance has deletion protection enabled.
Why it's wrong here
Deletion protection prevents deletion, not creation.
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.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which DOP-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.
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: An RDS instance with the same identifier already exists in the account and region. — Option B is correct because if the stack was previously deleted without retaining the resource, the DB instance may have been left behind. Option A is wrong because RDS does not have a deletion policy that prevents deletion. Option C is wrong because UpdateReplace policy would replace but not cause 'already exists' error. Option D is wrong because deletion protection would prevent deletion but not cause 'already exists' if the stack is new.
What should I do if I get this DOP-C02 question wrong?
Identify which DOP-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.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A startup is using AWS CloudFormation to manage their infrastructure. They have a stack that creates an Amazon S3 bucket and an Amazon DynamoDB table. The stack was created successfully, but when they try to update the stack to add a new S3 bucket, the update fails with the error 'CREATE_FAILED - S3 bucket already exists'. The new bucket name is unique and does not exist. The template uses the same AWS::S3::Bucket resource type. What is the most likely cause?
easy
A.The IAM user does not have permission to create S3 buckets.
✓ B.The S3 bucket name was previously used and is still in the process of being deleted (bucket name not yet released).
C.The stack is in a different region than where the bucket is being created.
D.The CloudFormation template uses the wrong resource type for the bucket.
Why B: Option A is correct because the bucket name may have been used in a previous stack and is in a deletion state. Option B is wrong because the account has permissions. Option C is wrong because the resource type is correct. Option D is wrong because the region is correct.
Last reviewed: Jun 20, 2026
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This DOP-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 DOP-C02 exam.
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