The answer is that the Batch Operations service role is missing the kms:GenerateDataKey permission for the destination KMS key. This is because S3 Batch Operations copying objects in place to apply SSE-KMS encryption requires the service role to have both kms:Decrypt for reading the source (if SSE-KMS) and kms:GenerateDataKey for writing the newly encrypted destination. Since the source objects use SSE-S3, which does not involve KMS, the only missing permission is kms:GenerateDataKey for the customer-managed key, causing the access denied error. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of the specific KMS actions needed for S3 Batch Operations during SSE-KMS migration, a common trap where engineers assume only kms:Decrypt is required. Remember the memory tip: “Decrypt to read, GenerateDataKey to write” — for SSE-S3 sources, you only need the write-side permission.
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 company uses Amazon EMR to process large datasets stored in Amazon S3. The data is encrypted at rest using SSE-S3. The security team now requires that all data at rest be encrypted with customer-managed KMS keys (SSE-KMS). The data engineer needs to migrate existing data to use SSE-KMS without downtime. The engineer plans to use S3 Batch Operations to copy objects in place. However, the Batch Operations job fails with a KMS access denied error. The engineer has confirmed that the Batch Operations service role has the necessary KMS permissions. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Batch Operations service role is missing the kms:GenerateDataKey permission for the destination KMS key.
Option D is correct because Batch Operations uses a service role that must have kms:Decrypt permission for the source objects and kms:GenerateDataKey for the destination. The source objects are encrypted with SSE-S3, which does not use KMS, so the service role does not need kms:Decrypt for source. However, the error indicates KMS access denied, likely because the service role does not have kms:GenerateDataKey for the destination KMS key. Option A is wrong because the service role is used. Option B is wrong because the source objects are SSE-S3. Option C is wrong because KMS key policy is for the destination key.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 policy does not allow the S3 service to use the key.
Why it's wrong here
The key policy must allow the Batch Operations service role.
✗
The Batch Operations job is using the wrong IAM role.
Why it's wrong here
The engineer confirmed the service role has permissions.
✗
The source objects are encrypted with SSE-S3, which cannot be copied to SSE-KMS.
Why it's wrong here
SSE-S3 objects can be copied to SSE-KMS.
✓
The Batch Operations service role is missing the kms:GenerateDataKey permission for the destination KMS key.
Why this is correct
Batch Operations needs to generate a new data key for the destination.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
Data Security and Governance — This question tests Data Security and Governance — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The Batch Operations service role is missing the kms:GenerateDataKey permission for the destination KMS key. — Option D is correct because Batch Operations uses a service role that must have kms:Decrypt permission for the source objects and kms:GenerateDataKey for the destination. The source objects are encrypted with SSE-S3, which does not use KMS, so the service role does not need kms:Decrypt for source. However, the error indicates KMS access denied, likely because the service role does not have kms:GenerateDataKey for the destination KMS key. Option A is wrong because the service role is used. Option B is wrong because the source objects are SSE-S3. Option C is wrong because KMS key policy is for the destination key.
What should I do if I get this DEA-C01 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
About these practice questions
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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. Refer to the exhibit. An IAM policy allows kms:Decrypt and kms:GenerateDataKey on a specific KMS key. A data engineer is unable to upload an object to an S3 bucket that uses SSE-KMS with that key. What is the MOST likely missing permission?
medium
A.kms:Decrypt permission on the key.
✓ B.s3:PutObject permission on the bucket.
C.kms:Encrypt permission on the key.
D.kms:CreateGrant permission on the key.
Why B: Option A is correct because to upload an object with SSE-KMS, the user needs kms:GenerateDataKey, which is already allowed, but also s3:PutObject permission on the bucket. Option B is wrong because kms:Decrypt is already allowed. Option C is wrong because kms:CreateGrant is not required for uploading. Option D is wrong because kms:Encrypt is not required; GenerateDataKey is sufficient.
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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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