The answer is to create a customer-managed KMS key, configure default encryption on the bucket to use SSE-KMS with that key, and add a bucket policy that denies any s3:PutObject request that does not include the x-amz-server-side-encryption header set to aws:kms. This combination works because default encryption handles objects uploaded without explicit encryption instructions, while the bucket policy acts as a hard gate, rejecting any upload that tries to bypass KMS encryption entirely. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of the layered defense between S3 default encryption and bucket policies, a common trap being that default encryption alone does not enforce encryption on API calls that explicitly set a different encryption type. Remember the memory tip: “Default for the lazy, policy for the crazy”—default encryption catches unencrypted uploads, but only a bucket policy can deny non-KMS encryption attempts outright.
DEA-C01 Data Store Management Practice Question
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 company is using Amazon S3 for a data lake. The data engineer needs to ensure that all new objects are automatically encrypted with a customer-managed KMS key and that the bucket policy enforces encryption. Which THREE steps should be taken? (Choose THREE.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure default encryption on the bucket to use SSE-KMS.
Option A is correct because configuring default encryption on the S3 bucket to use SSE-KMS ensures that any object uploaded without an explicit encryption header is automatically encrypted with the specified customer-managed KMS key. This satisfies the requirement for automatic encryption of all new objects.
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.
✓
Configure default encryption on the bucket to use SSE-KMS.
Why this is correct
Ensures new objects are encrypted with SSE-KMS by default.
Related concept
Read the scenario before looking for a memorised answer.
✓
Add a bucket policy that denies PutObject if the x-amz-server-side-encryption header is not set to aws:kms.
Why this is correct
Enforces encryption on every upload.
Related concept
Read the scenario before looking for a memorised answer.
✓
Create a customer-managed KMS key.
Why this is correct
Required for SSE-KMS with customer-managed key.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a lifecycle policy to apply encryption to existing objects.
Why it's wrong here
Lifecycle policies do not apply encryption retroactively.
✗
Enable AWS CloudTrail to monitor encryption.
Why it's wrong here
Logging does not enforce encryption.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse lifecycle policies (which manage object transitions) with encryption enforcement, or they think CloudTrail can enforce encryption rather than just audit it.
Detailed technical explanation
How to think about this question
When default encryption is set to SSE-KMS, S3 automatically adds the `x-amz-server-side-encryption: aws:kms` header to PUT requests that lack it, and the bucket policy can then deny any PutObject that does not include this header. This combination ensures that every new object is encrypted with the customer-managed KMS key, and the policy enforces compliance even if the client omits the header. Under the hood, S3 intercepts the request and calls KMS to generate a data key, which is used to encrypt the object before storage.
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: Configure default encryption on the bucket to use SSE-KMS. — Option A is correct because configuring default encryption on the S3 bucket to use SSE-KMS ensures that any object uploaded without an explicit encryption header is automatically encrypted with the specified customer-managed KMS key. This satisfies the requirement for automatic encryption of all new objects.
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 →
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 company uses Amazon S3 as its data lake. A data engineer needs to enforce encryption of data at rest using server-side encryption with AWS KMS. Which S3 bucket property should be configured?
easy
✓ A.Default encryption
B.Server access logging
C.Versioning
D.Bucket policy
Why A: Option A is correct because configuring default encryption on an S3 bucket ensures that all objects stored in the bucket are encrypted at rest using server-side encryption. When AWS KMS is specified as the encryption type, S3 automatically encrypts objects with a KMS key (SSE-KMS) upon upload, even if the upload request does not include encryption headers. This enforces encryption at rest without requiring changes to client applications.
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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
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