The answer is that the upload fails because the object is not encrypted with SSE-KMS. The bucket policy includes a condition that denies s3:PutObject unless the x-amz-server-side-encryption header is set to aws:kms, and the CLI command aws s3 cp does not include the --sse aws:kms flag, so the request is blocked. This scenario tests your understanding of how S3 bucket policies enforce SSE-KMS encryption by evaluating request headers against policy conditions like StringNotEquals. On the AWS Certified Data Engineer Associate DEA-C01 exam, this is a common trap: candidates assume the CLI defaults to KMS encryption, but it does not—you must explicitly specify it. A helpful memory tip is “No flag, no KMS—policy denies the upload unless you specify aws:kms.”
DEA-C01 Data Security and Governance Practice Question
This DEA-C01 practice question tests your understanding of data security and governance. 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.
Exhibit
Refer to the exhibit.
ERROR: An error occurred (AccessDenied) when calling the PutObject operation: Access Denied
Bucket policy snippet:
{
"Effect": "Deny",
"Principal": "*",
"Action": "s3:PutObject",
"Resource": "arn:aws:s3:::my-bucket/*",
"Condition": {
"StringNotEquals": {
"s3:x-amz-server-side-encryption": "aws:kms"
}
}
}
A data engineer receives the error shown in the exhibit when trying to upload a file to my-bucket. The engineer uses the AWS CLI with the following command: aws s3 cp file.txt s3://my-bucket/. What is the most likely cause of the error?
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
✓
The object is not encrypted with SSE-KMS
Option B is correct because the bucket policy denies PutObject if the encryption header is not set to aws:kms (SSE-KMS). The CLI command does not specify encryption, so the condition StringNotEquals matches and denies the request. Option A is wrong because the bucket policy explicitly denies non-KMS encrypted uploads. Option C is wrong because the error is not a network issue. Option D is wrong because the policy does not require KMS key ID, just the header value.
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 KMS key specified in the command is incorrect
Why it's wrong here
The command does not specify any KMS key.
✗
The VPC endpoint policy is blocking the request
Why it's wrong here
The error message indicates an S3 access denied, not network.
✓
The object is not encrypted with SSE-KMS
Why this is correct
The policy requires SSE-KMS encryption header.
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 bucket does not have a default encryption configuration
Why it's wrong here
Default encryption would not override the bucket policy.
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.
Trap categories for this question
Command / output trap
The command does not specify any KMS key.
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 Security and Governance — This question tests Data Security and Governance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The object is not encrypted with SSE-KMS — Option B is correct because the bucket policy denies PutObject if the encryption header is not set to aws:kms (SSE-KMS). The CLI command does not specify encryption, so the condition StringNotEquals matches and denies the request. Option A is wrong because the bucket policy explicitly denies non-KMS encrypted uploads. Option C is wrong because the error is not a network issue. Option D is wrong because the policy does not require KMS key ID, just the header value.
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.
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.
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