This DEA-C01 practice question tests your understanding of data store management. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 data engineer is reviewing an IAM policy that controls access to an S3 bucket. The policy is attached to a user group. The engineer notices that users are unable to download objects from the bucket. What is the likely cause?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The objects are encrypted using SSE-KMS, not SSE-S3.
The correct answer is D because when objects are encrypted with SSE-KMS, the IAM policy must explicitly grant the `kms:Decrypt` permission for the KMS key used to encrypt the objects. Without this permission, even if the S3 policy allows `s3:GetObject`, the download will fail because the decryption step is blocked. This is a common scenario where the encryption method (SSE-KMS) introduces an additional authorization requirement that is overlooked. The other options are less likely: attaching the policy to a user group is valid and does not cause download issues; an incorrect bucket ARN would affect all operations, not just downloads; and missing `s3:GetObject` would be a straightforward policy error that would be easily identified.
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 is attached to a user group instead of an IAM role.
Why it's wrong here
Attaching to a group is valid; the issue is the condition.
✗
The policy does not specify the correct bucket ARN.
Why it's wrong here
The ARN is correct: arn:aws:s3:::my-bucket/*.
✗
The policy does not allow the s3:GetObject action.
Why it's wrong here
The policy explicitly allows s3:GetObject.
✓
The objects are encrypted using SSE-KMS, not SSE-S3.
Why this is correct
The condition requires SSE-S3 (AES256), so SSE-KMS objects are denied.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often focus only on S3 actions (like `s3:GetObject`) and overlook the required KMS permissions when SSE-KMS is involved, assuming SSE-S3 or no encryption is the default.
Detailed technical explanation
How to think about this question
Under the hood, when SSE-KMS is used, S3 calls KMS to decrypt the object on behalf of the user. The user must have `kms:Decrypt` permission on the specific KMS key (identified by its ARN) in addition to `s3:GetObject`. This is a two-step authorization: S3 policy controls access to the object, and KMS policy controls access to the encryption key. A real-world scenario is when a data lake uses SSE-KMS for compliance, and data engineers forget to add the KMS decrypt permission to the IAM policy, causing silent download 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 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.
Quick reference
AWS S3 Storage Class Comparison
Storage Class
Min Duration
Retrieval
Use Case
S3 Standard
None
Immediate
Frequently accessed data
S3 Standard-IA
30 days
Immediate
Infrequent access, rapid retrieval
S3 One Zone-IA
30 days
Immediate
Non-critical infrequent data
S3 Intelligent-Tiering
None
Immediate–hours
Unknown or changing access patterns
S3 Glacier Instant
90 days
Milliseconds
Archive with instant retrieval
S3 Glacier Flexible
90 days
Minutes–hours
Archive, flexible retrieval
S3 Glacier Deep Archive
180 days
Hours
Long-term compliance archive
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.
Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The objects are encrypted using SSE-KMS, not SSE-S3. — The correct answer is D because when objects are encrypted with SSE-KMS, the IAM policy must explicitly grant the `kms:Decrypt` permission for the KMS key used to encrypt the objects. Without this permission, even if the S3 policy allows `s3:GetObject`, the download will fail because the decryption step is blocked. This is a common scenario where the encryption method (SSE-KMS) introduces an additional authorization requirement that is overlooked. The other options are less likely: attaching the policy to a user group is valid and does not cause download issues; an incorrect bucket ARN would affect all operations, not just downloads; and missing `s3:GetObject` would be a straightforward policy error that would be easily identified.
What should I do if I get this DEA-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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 →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This DEA-C01 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 DEA-C01 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.