The correct answer requires three steps: adding a statement to the KMS key policy allowing kms:Decrypt for the specific IAM roles, ensuring each role has an IAM policy that also allows kms:Decrypt, and including kms:GenerateDataKey permission in the key policy for encryption. This layered approach works because KMS key policies act as the primary access control boundary—without a key policy grant, even an IAM role with full permissions cannot decrypt. On the AWS Certified Data Engineer Associate DEA-C01 exam, this tests your understanding of the KMS authorization model, where both the key policy and IAM policy must align for decryption to succeed. A common trap is assuming IAM policies alone suffice; remember that KMS key policies explicitly grant access to principals, and by default IAM policies are allowed unless the key policy denies them. Memory tip: "Key policy first, IAM second—decrypt only works when both are beckoned."
DEA-C01 Data Security and Governance Practice Question
This DEA-C01 practice question tests your understanding of data security and governance. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 AWS KMS to encrypt data in multiple services. They want to ensure that only specific IAM roles can decrypt data using a particular KMS key. Which THREE steps are necessary?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Attach an IAM policy to each role with kms:Decrypt permission
The KMS key policy must grant decrypt permission to the IAM roles. Each role must have an IAM policy allowing kms:Decrypt. Additionally, the key policy should also grant kms:GenerateDataKey for encryption. Option D is wrong because the key policy does not need to enable IAM policies; by default, IAM policies are allowed unless the key policy denies them. Option E is wrong because key rotation is not required for access control.
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.
✓
Attach an IAM policy to each role with kms:Decrypt permission
Why this is correct
The roles need an IAM policy that allows decrypt actions.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enable IAM policies in the key policy
Why it's wrong here
By default, IAM policies are allowed; this option is not a separate step.
✗
Enable automatic key rotation
Why it's wrong here
Key rotation does not affect access control.
✓
Ensure the key policy allows kms:GenerateDataKey for the roles
Why this is correct
To encrypt, the roles need GenerateDataKey permission.
Related concept
Read the scenario before looking for a memorised answer.
✓
Add a statement to the KMS key policy allowing kms:Decrypt for the IAM roles
Why this is correct
The key policy must explicitly allow the roles to decrypt.
Related concept
Read the scenario before looking for a memorised answer.
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.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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: Attach an IAM policy to each role with kms:Decrypt permission — The KMS key policy must grant decrypt permission to the IAM roles. Each role must have an IAM policy allowing kms:Decrypt. Additionally, the key policy should also grant kms:GenerateDataKey for encryption. Option D is wrong because the key policy does not need to enable IAM policies; by default, IAM policies are allowed unless the key policy denies them. Option E is wrong because key rotation is not required for access control.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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