The answer is to enable default encryption on the S3 bucket with SSE-KMS. This is correct because a bucket policy that denies PutObject unless the `x-amz-server-side-encryption: aws:kms` header is present only blocks requests that include an incorrect or missing header value, but it does not deny requests that omit the header entirely—those requests simply bypass the condition check and succeed. Default encryption closes this gap by automatically applying SSE-KMS to any object uploaded without an explicit encryption header, ensuring no unencrypted object can be stored. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of the interaction between bucket policies and default encryption, a common trap where candidates assume a deny policy alone is sufficient. Remember the memory tip: “Policies check headers, defaults cover gaps”—always pair a conditional policy with default encryption to enforce SSE-KMS comprehensively.
DEA-C01 Data Store Management Practice Question
This DEA-C01 practice question tests your understanding of data store management. 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 company uses Amazon S3 to store sensitive documents. The security team has mandated that all objects must be encrypted at rest using server-side encryption with AWS KMS (SSE-KMS). Additionally, the company wants to ensure that any attempt to upload an unencrypted object is denied. A data engineer has configured a bucket policy that denies PutObject if the encryption header does not include x-amz-server-side-encryption: aws:kms. However, the engineer notices that some objects are still being stored without encryption. Upon investigation, the engineer suspects that the policy is not being evaluated correctly. What should the engineer do to ensure that all objects are encrypted with SSE-KMS?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable default encryption on the S3 bucket with SSE-KMS.
Option D is correct because enabling default encryption on the S3 bucket with SSE-KMS ensures that any object uploaded without an explicit encryption header is automatically encrypted with SSE-KMS. This closes the gap where the bucket policy condition fails to catch uploads that omit the `x-amz-server-side-encryption` header entirely, as the policy only denies requests with an incorrect header but does not block requests that lack the header altogether. Default encryption applies server-side encryption at the bucket level, making it impossible to store an unencrypted object.
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.
✗
Use an IAM policy to require encryption instead of a bucket policy.
Why it's wrong here
IAM policies can require encryption, but bucket policies are more direct.
✗
Enable S3 Block Public Access settings.
Why it's wrong here
Block Public Access does not enforce encryption.
✗
Add a condition to the bucket policy that checks for aws:SourceVpce.
Why it's wrong here
This condition is for VPC endpoint, not encryption.
✓
Enable default encryption on the S3 bucket with SSE-KMS.
Why this is correct
Default encryption ensures all objects are encrypted, complementing the bucket policy.
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 assume a bucket policy condition denying PutObject without `x-amz-server-side-encryption: aws:kms` will block all unencrypted uploads, but they overlook that the condition only matches when the header is present with a wrong value, not when the header is absent entirely.
Detailed technical explanation
How to think about this question
Under the hood, S3 bucket policies with `aws:SecureTransport` or `s3:x-amz-server-side-encryption` conditions only evaluate headers present in the request; if a client omits the encryption header entirely, the condition key is not present and the policy's Deny effect may not trigger, allowing the upload to succeed without encryption. Default encryption on the bucket applies SSE-KMS to all objects at write time, regardless of the request headers, effectively enforcing encryption even when the bucket policy condition fails. In real-world scenarios, this is a common misconfiguration where engineers rely solely on policy conditions without enabling default encryption, leading to compliance gaps.
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.
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: Enable default encryption on the S3 bucket with SSE-KMS. — Option D is correct because enabling default encryption on the S3 bucket with SSE-KMS ensures that any object uploaded without an explicit encryption header is automatically encrypted with SSE-KMS. This closes the gap where the bucket policy condition fails to catch uploads that omit the `x-amz-server-side-encryption` header entirely, as the policy only denies requests with an incorrect header but does not block requests that lack the header altogether. Default encryption applies server-side encryption at the bucket level, making it impossible to store an unencrypted object.
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.