Quick Answer
The answer is that the KMS key policy is missing the Encrypt action, which directly causes the access denied error. AWS KMS key policies function as the primary access control mechanism, and when a policy explicitly lists allowed actions, only those actions are permitted; without kms:Encrypt in the Action list, the DataEngineer role can decrypt and re-encrypt but cannot perform the initial encryption operation. This scenario tests your understanding of how KMS key policies use an implicit deny model—any action not explicitly allowed is denied by default, regardless of the principal or resource being correct. On the AWS Certified Data Engineer Associate DEA-C01 exam, this is a common trap where candidates focus on the principal or resource fields but overlook the missing action. A helpful memory tip is "If it's not in the list, it doesn't exist"—always check that every required API action is explicitly listed in the key policy.
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.
Refer to the exhibit.
Exhibit:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"AWS": "arn:aws:iam::123456789012:role/DataEngineer"
},
"Action": ["kms:Decrypt", "kms:ReEncrypt*"
],
"Resource": "*"
}
]
}A data engineer tries to encrypt data using the KMS key associated with this key policy and receives an access denied error. What is the cause?
The principal is an IAM role, which is not allowed
Why wrong: IAM roles are allowed as principals.
There is an explicit deny in the policy
Why wrong: No explicit deny is present.
The Resource element is set to "*", which is invalid for KMS key policies
Why wrong: "*" is valid for KMS key policies.
The policy does not include kms:Encrypt action
Encrypt action is missing.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The policy does not include kms:Encrypt action
Option B is correct. The key policy grants Decrypt and ReEncrypt, but not Encrypt. Option A is wrong because the resource is "*" which means all keys. Option C is wrong because the principal is correct. Option D is wrong because there is no explicit deny.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The principal is an IAM role, which is not allowed
Why it's wrong here
IAM roles are allowed as principals.
There is an explicit deny in the policy
Why it's wrong here
No explicit deny is present.
The Resource element is set to "*", which is invalid for KMS key policies
Why it's wrong here
"*" is valid for KMS key policies.
The policy does not include kms:Encrypt action
Why this is correct
Encrypt action is missing.
Related concept
Standard ACLs match source addresses.
Common exam traps
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
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
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
Data Security and Governance — study guide chapter
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FAQ
Data Security and Governance — This question tests Data Security and Governance — Standard ACLs match source addresses..
The correct answer is: The policy does not include kms:Encrypt action — Option B is correct. The key policy grants Decrypt and ReEncrypt, but not Encrypt. Option A is wrong because the resource is "*" which means all keys. Option C is wrong because the principal is correct. Option D is wrong because there is no explicit deny.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
Standard ACLs match source addresses.
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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.
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