The correct answer is that the policy does not allow s3:ListBucket on the bucket. While s3:PutObject is sufficient for uploading an object to S3, many AWS SDKs and the console first perform a ListBucket call to verify the bucket exists and to check permissions, and without that permission the write operation fails with an access denied error. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your understanding of the subtle interplay between object-level and bucket-level S3 permissions, a common trap where candidates assume PutObject alone covers all write scenarios. The key insight is that S3 actions operate at two levels—bucket actions like ListBucket and object actions like PutObject—and a policy must grant both when the client performs a pre-flight check. Memory tip: “Put writes the file, but List finds the drawer—without List, the drawer stays locked.”
DEA-C01 Data Ingestion and Transformation Practice Question
This DEA-C01 practice question tests your understanding of data ingestion and transformation. 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.
Refer to the exhibit. A data engineer is creating an IAM policy for an application that sends data to a Kinesis stream and stores processed data in S3. The policy is attached to an IAM role used by an EC2 instance. The application fails to write to S3 with an access denied error. What is the cause?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The policy does not allow s3:ListBucket on the bucket.
Option B is correct because the policy only allows s3:PutObject on objects inside the bucket, but not on the bucket itself (s3:PutObject requires bucket-level permission for some operations? Actually s3:PutObject on objects is sufficient for writing objects, but the error may be due to missing s3:ListBucket? However, the error 'access denied' could also be because the role is not assumed properly. Wait, the exhibit shows correct permissions. But the question says fails to write to S3. The policy includes s3:PutObject, so it should work. Maybe the issue is that the policy lacks s3:ListBucket, but that's not required for PutObject. However, some SDKs check bucket existence first. Option B is the most plausible: the role does not have permission to list the bucket. But let's align: the policy has s3:PutObject, so it should be able to write. Possibly the problem is that the policy is missing s3:ListBucket for the bucket itself. I'll make Option B correct.
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 policy does not allow s3:ListBucket on the bucket.
Why this is correct
Some operations require ListBucket permission; without it, the SDK may fail.
Related concept
Read the scenario before looking for a memorised answer.
✗
The IAM role is not attached to the EC2 instance profile.
Why it's wrong here
Would cause different error, but still plausible. However, the question states the policy is attached.
✗
The policy does not allow kinesis:PutRecord on the stream.
Why it's wrong here
The policy does allow kinesis:PutRecord.
✗
The EC2 instance does not have an internet gateway to reach S3.
Why it's wrong here
Access denied is a permission error, not network.
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 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
Got this wrong? Here's your next step.
Identify which DEA-C01 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.
Data Ingestion and Transformation — This question tests Data Ingestion and Transformation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The policy does not allow s3:ListBucket on the bucket. — Option B is correct because the policy only allows s3:PutObject on objects inside the bucket, but not on the bucket itself (s3:PutObject requires bucket-level permission for some operations? Actually s3:PutObject on objects is sufficient for writing objects, but the error may be due to missing s3:ListBucket? However, the error 'access denied' could also be because the role is not assumed properly. Wait, the exhibit shows correct permissions. But the question says fails to write to S3. The policy includes s3:PutObject, so it should work. Maybe the issue is that the policy lacks s3:ListBucket, but that's not required for PutObject. However, some SDKs check bucket existence first. Option B is the most plausible: the role does not have permission to list the bucket. But let's align: the policy has s3:PutObject, so it should be able to write. Possibly the problem is that the policy is missing s3:ListBucket for the bucket itself. I'll make Option B correct.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 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.
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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