- A
The KMS key rotation created a new backing key, but the Glue job's IAM role does not have permission to decrypt with the old backing key.
If automatic rotation is enabled, old backing keys are retained, but if the key was manually rotated (new key created), the old key may be disabled. Also, the key policy may have been updated incorrectly.
- B
The Glue job's IAM role is missing the kms:Encrypt permission on the KMS key.
Why wrong: kms:Encrypt is not needed for reading encrypted data.
- C
The Glue job is using the wrong encryption context when calling KMS.
Why wrong: Encryption context mismatches can cause failures, but rotation does not change the encryption context.
- D
The S3 bucket policy has a condition that requires the request to use the latest version of the KMS key.
Why wrong: S3 bucket policies do not have such conditions; they can use kms:EncryptionContext but not key version.
Quick Answer
The answer is that the KMS key rotation created a new backing key, but the Glue job's IAM role does not have permission to decrypt with the old backing key. When you rotate a customer managed KMS key, AWS KMS retains the previous backing key material so that data encrypted before the rotation can still be decrypted, but the IAM role must explicitly be allowed to use that old key version via the kms:Decrypt action. If the key policy or IAM policy was inadvertently narrowed during rotation—or if it never granted access to the older key material—the Glue ETL job will fail with AccessDenied when reading SSE-KMS encrypted objects from the source bucket. This scenario tests your understanding that KMS key rotation does not automatically re-encrypt existing data; the old backing key remains in use for decryption, and permissions must cover all key versions. On the DEA-C01 exam, this is a common trap where candidates assume rotation is seamless, but the real issue is that the IAM role lacks explicit decrypt rights for the prior key version. Memory tip: “Rotate the key, not the permissions—old data still needs old key access.”
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.
A healthcare company uses AWS Glue to process patient data stored in Amazon S3. The data is encrypted at rest using SSE-KMS with a customer managed key. The Glue ETL job runs on a schedule and reads from an S3 bucket, transforms the data, and writes to another S3 bucket also encrypted with the same KMS key. Recently, the security team rotated the KMS key. After the rotation, the Glue job started failing with 'AccessDenied' errors when trying to read from the source bucket. The Glue job's IAM role has permissions to use the KMS key (kms:Decrypt, kms:GenerateDataKey). The S3 bucket policies allow the role to read/write. What is the MOST likely cause of the failure?
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 choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The KMS key rotation created a new backing key, but the Glue job's IAM role does not have permission to decrypt with the old backing key.
When you rotate a customer managed KMS key, AWS KMS retains the old backing key to allow decryption of data encrypted before the rotation. However, the Glue job's IAM role must have permission to use the old backing key via the kms:Decrypt action. If the key policy or IAM policy does not explicitly allow decryption with the old backing key (or if the key policy was inadvertently updated to remove access to the old key material), the Glue job will fail with AccessDenied when reading SSE-KMS encrypted objects that were encrypted with the previous key version.
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 rotation created a new backing key, but the Glue job's IAM role does not have permission to decrypt with the old backing key.
Why this is correct
If automatic rotation is enabled, old backing keys are retained, but if the key was manually rotated (new key created), the old key may be disabled. Also, the key policy may have been updated incorrectly.
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's IAM role is missing the kms:Encrypt permission on the KMS key.
Why it's wrong here
kms:Encrypt is not needed for reading encrypted data.
- ✗
The Glue job is using the wrong encryption context when calling KMS.
Why it's wrong here
Encryption context mismatches can cause failures, but rotation does not change the encryption context.
- ✗
The S3 bucket policy has a condition that requires the request to use the latest version of the KMS key.
Why it's wrong here
S3 bucket policies do not have such conditions; they can use kms:EncryptionContext but not key version.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume KMS key rotation is seamless and never breaks existing access, but they overlook that the IAM role or key policy must still grant kms:Decrypt on the key resource, and that the old backing key remains in use for previously encrypted data.
Detailed technical explanation
How to think about this question
Under the hood, AWS KMS key rotation creates a new cryptographic backing key, but the old backing key remains active for decryption. The kms:Decrypt permission applies to the key as a whole, not to a specific version, but the key policy must grant access to the key resource itself. In practice, if the key policy was modified during rotation (e.g., to restrict usage to a specific principal or condition), the old backing key may become inaccessible. This scenario is common when using cross-account KMS keys or when the key policy includes a condition that inadvertently blocks decryption of older ciphertexts.
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.
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FAQ
Questions learners often ask
What does this DEA-C01 question test?
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 KMS key rotation created a new backing key, but the Glue job's IAM role does not have permission to decrypt with the old backing key. — When you rotate a customer managed KMS key, AWS KMS retains the old backing key to allow decryption of data encrypted before the rotation. However, the Glue job's IAM role must have permission to use the old backing key via the kms:Decrypt action. If the key policy or IAM policy does not explicitly allow decryption with the old backing key (or if the key policy was inadvertently updated to remove access to the old key material), the Glue job will fail with AccessDenied when reading SSE-KMS encrypted objects that were encrypted with the previous key version.
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.
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Last reviewed: Jun 11, 2026
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.
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