The answer is that the IAM role used by the Glue job is missing the kms:Decrypt permission. This is correct because when an S3 bucket uses SSE-KMS with a customer-managed KMS key, any service reading from that bucket—including AWS Glue—must have explicit kms:Decrypt permission on that key. Without it, the Glue job cannot decrypt the S3 objects during the read operation, triggering the access failure. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how KMS permissions interact with S3 encryption at the service level, often appearing as a trap where candidates mistakenly focus on S3 bucket policies instead of the Glue job’s IAM role. A common memory tip: remember that SSE-KMS decryption is a two-step handshake—S3 grants read access, but the KMS key must separately grant decrypt access to the caller. Think “S3 opens the door, KMS unlocks the box.”
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 from AWS Glue job:
```
ERROR: An error occurred while calling o75.pyWriteDynamicFrame.
Access Denied. User: arn:aws:sts::123456789012:assumed-role/GlueServiceRole/i-abc123 is not authorized to perform: kms:Decrypt on resource: arn:aws:kms:us-east-1:123456789012:key/mrk-1234567890 because no identity-based policy allows the kms:Decrypt action
```
Refer to the exhibit. A data engineer is running an AWS Glue job that reads from an S3 bucket encrypted with a customer-managed KMS key. The job fails with the error shown. What is the most likely cause?
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.
Refer to the exhibit.
Error from AWS Glue job:
```
ERROR: An error occurred while calling o75.pyWriteDynamicFrame.
Access Denied. User: arn:aws:sts::123456789012:assumed-role/GlueServiceRole/i-abc123 is not authorized to perform: kms:Decrypt on resource: arn:aws:kms:us-east-1:123456789012:key/mrk-1234567890 because no identity-based policy allows the kms:Decrypt action
```
A
The S3 bucket policy denies the kms:Decrypt action.
Why wrong: The error points to identity-based policy, not bucket policy.
B
The IAM role used by the Glue job is missing the kms:Decrypt permission.
The error says no identity-based policy allows kms:Decrypt.
C
The Glue job does not have permission to call kms:GenerateDataKey.
Why wrong: The error specifies kms:Decrypt, not GenerateDataKey.
D
The KMS key policy does not grant the Glue service principal access.
Why wrong: The role is used, not the service principal directly.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The IAM role used by the Glue job is missing the kms:Decrypt permission.
The error indicates that the AWS Glue job cannot access the S3 bucket because it lacks the necessary KMS permissions. Since the bucket is encrypted with a customer-managed KMS key, the IAM role assigned to the Glue job must include the kms:Decrypt permission to read the encrypted objects. Without this permission, the job fails when attempting to decrypt the data.
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 S3 bucket policy denies the kms:Decrypt action.
Why it's wrong here
The error points to identity-based policy, not bucket policy.
✓
The IAM role used by the Glue job is missing the kms:Decrypt permission.
Why this is correct
The error says no identity-based policy allows kms:Decrypt.
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 Glue job does not have permission to call kms:GenerateDataKey.
Why it's wrong here
The error specifies kms:Decrypt, not GenerateDataKey.
✗
The KMS key policy does not grant the Glue service principal access.
Why it's wrong here
The role is used, not the service principal directly.
Common exam traps
Common exam trap: answer the scenario, not the keyword
AWS often tests the distinction between kms:Decrypt and kms:GenerateDataKey, leading candidates to mistakenly choose the latter when the job is only reading data, not writing or generating new encryption keys.
Detailed technical explanation
How to think about this question
When an S3 object is encrypted with a customer-managed KMS key, the AWS Glue job must have the kms:Decrypt permission on that key to read the object. The IAM role assumed by the Glue job must include this permission in its attached policies, and the KMS key policy must also grant access to that role (or the account). The error message 'AccessDenied' when calling KMS is a clear indicator that the IAM role lacks the required kms:Decrypt action, not that the key policy is misconfigured or that a different KMS action is missing.
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 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 IAM role used by the Glue job is missing the kms:Decrypt permission. — The error indicates that the AWS Glue job cannot access the S3 bucket because it lacks the necessary KMS permissions. Since the bucket is encrypted with a customer-managed KMS key, the IAM role assigned to the Glue job must include the kms:Decrypt permission to read the encrypted objects. Without this permission, the job fails when attempting to decrypt the data.
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.
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.
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 data engineer is troubleshooting an issue where an IAM role used by AWS Glue cannot read data from an S3 bucket encrypted with SSE-KMS. The bucket policy allows the role to perform s3:GetObject. What additional permission is needed?
hard
A.s3:GetObjectVersion
✓ B.kms:Decrypt on the KMS key
C.s3:GetObjectAcl
D.kms:GenerateDataKey on the KMS key
Why B: For SSE-KMS, the IAM role must have kms:Decrypt permission on the KMS key. Option A is wrong because s3:GetObject is already allowed. Option B is wrong because SSE-KMS does not require s3:GetObjectAcl. Option D is wrong because kms:GenerateDataKey is used for writes. Option C is correct.
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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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