Quick Answer
The answer is the kms:Decrypt permission. When an S3 bucket uses SSE-KMS (Server-Side Encryption with AWS KMS), reading any object requires the IAM role to have explicit permission to call the KMS Decrypt API, because the object’s data is encrypted at rest with a customer master key. Without this permission, even if the role has s3:GetObject, the encrypted ciphertext cannot be decrypted, causing the ETL job to fail. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how KMS permissions interact with S3 access policies—a common trap is assuming s3:GetObject alone is sufficient. Remember, SSE-KMS adds a separate decryption authorization layer: you need both S3 read access and kms:Decrypt. A useful memory tip is “Get the object, then decrypt the key”—two actions, two permissions.
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 data engineer is troubleshooting an ETL job that reads from an S3 bucket encrypted with SSE-KMS. The job is failing with an error indicating that the IAM role does not have permission to decrypt the data. What is the most likely missing permission?
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.
kms:GenerateDataKey
Why wrong: GenerateDataKey is used for encryption, not decryption.
s3:ListBucket
Why wrong: ListBucket is for listing objects, not reading encrypted data.
kms:Decrypt
To read SSE-KMS encrypted objects, the role must have kms:Decrypt permission on the KMS key.
s3:GetObject
Why wrong: GetObject alone is insufficient without decrypt permission on the KMS key.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
kms:Decrypt
Option D is correct because the role needs kms:Decrypt to read data encrypted with KMS keys. Option A is wrong because s3:ListBucket allows listing, not reading. Option B is wrong because s3:GetObject allows reading but without decrypt permission, the encrypted object cannot be read. Option C is wrong because kms:GenerateDataKey is for encryption, not decryption.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
kms:GenerateDataKey
Why it's wrong here
GenerateDataKey is used for encryption, not decryption.
s3:ListBucket
Why it's wrong here
ListBucket is for listing objects, not reading encrypted data.
kms:Decrypt
Why this is correct
To read SSE-KMS encrypted objects, the role must have kms:Decrypt permission on the KMS key.
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.
s3:GetObject
Why it's wrong here
GetObject alone is insufficient without decrypt permission on the KMS key.
Common exam traps
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.
Detailed technical explanation
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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 — study guide chapter
Learn the concepts, then practise the questions
Data Security and Governance practice questions
Targeted practice on this topic area only
All DEA-C01 questions
1,786 questions across all exam domains
AWS Certified Data Engineer Associate DEA-C01 study guide
Full concept coverage aligned to exam objectives
DEA-C01 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise DEA-C01 questions linked to Data Ingestion and Transformation.
Practise DEA-C01 questions linked to Data Operations and Support.
Practise DEA-C01 questions linked to Data Security and Governance.
Practise DEA-C01 questions linked to Data Store Management.
Practise DEA-C01 questions linked to DEA-C01 fundamentals.
Practise DEA-C01 questions linked to DEA-C01 scenario.
Practise DEA-C01 questions linked to DEA-C01 troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Data Security and Governance — This question tests Data Security and Governance — Read the scenario before looking for a memorised answer..
The correct answer is: kms:Decrypt — Option D is correct because the role needs kms:Decrypt to read data encrypted with KMS keys. Option A is wrong because s3:ListBucket allows listing, not reading. Option B is wrong because s3:GetObject allows reading but without decrypt permission, the encrypted object cannot be read. Option C is wrong because kms:GenerateDataKey is for encryption, not decryption.
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.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 →
Last reviewed: Jun 20, 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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.