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.
Refer to the exhibit. A data engineer creates this KMS key policy. An IAM role in account 123456789012 is granted decrypt access to the key. However, when the DataAnalystRole tries to decrypt an S3 object encrypted with this key, the operation fails. What is the most likely reason?
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.
The S3 bucket policy does not allow the role to call s3:GetObject
Even with decrypt permission, the role needs s3:GetObject permission on the encrypted object.
B
The KMS key is in a different region than the S3 bucket
Why wrong: Cross-region access is possible with appropriate policies, but the key policy is in us-east-1; if bucket is in another region, cross-region calls are allowed if both policies permit.
C
The role does not have permission to call kms:DescribeKey
Why wrong: The policy grants DescribeKey; decryption only requires Decrypt, not DescribeKey.
D
The KMS key policy does not grant kms:Decrypt permission to the role
Why wrong: The policy grants kms:Decrypt and kms:DescribeKey.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The S3 bucket policy does not allow the role to call s3:GetObject
KMS key policies grant access to principals. However, if the S3 bucket policy does not allow the role to call kms:Decrypt, the combination of policies might still deny. But the key policy itself grants decrypt. A common issue is that the S3 bucket policy might not allow the s3:GetObject action, or the role might not have S3 permissions. Another possibility is that the KMS key is in a different region (us-east-1) but the S3 object is in another region, causing cross-region access which is not allowed by default. However, the most likely reason based on typical exam scenarios is that the S3 bucket policy does not grant the necessary S3 permissions.
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
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The S3 bucket policy does not allow the role to call s3:GetObject
Why this is correct
Even with decrypt permission, the role needs s3:GetObject permission on the encrypted object.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Standard ACLs match source addresses.
✗
The KMS key is in a different region than the S3 bucket
Why it's wrong here
Cross-region access is possible with appropriate policies, but the key policy is in us-east-1; if bucket is in another region, cross-region calls are allowed if both policies permit.
✗
The role does not have permission to call kms:DescribeKey
Why it's wrong here
The policy grants DescribeKey; decryption only requires Decrypt, not DescribeKey.
✗
The KMS key policy does not grant kms:Decrypt permission to the role
Why it's wrong here
The policy grants kms:Decrypt and kms:DescribeKey.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
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.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
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
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.
Quick reference
AWS S3 Storage Class Comparison
Storage Class
Min Duration
Retrieval
Use Case
S3 Standard
None
Immediate
Frequently accessed data
S3 Standard-IA
30 days
Immediate
Infrequent access, rapid retrieval
S3 One Zone-IA
30 days
Immediate
Non-critical infrequent data
S3 Intelligent-Tiering
None
Immediate–hours
Unknown or changing access patterns
S3 Glacier Instant
90 days
Milliseconds
Archive with instant retrieval
S3 Glacier Flexible
90 days
Minutes–hours
Archive, flexible retrieval
S3 Glacier Deep Archive
180 days
Hours
Long-term compliance archive
What to study next
Got this wrong? Here's your next step.
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 — This question tests Data Security and Governance — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: The S3 bucket policy does not allow the role to call s3:GetObject — KMS key policies grant access to principals. However, if the S3 bucket policy does not allow the role to call kms:Decrypt, the combination of policies might still deny. But the key policy itself grants decrypt. A common issue is that the S3 bucket policy might not allow the s3:GetObject action, or the role might not have S3 permissions. Another possibility is that the KMS key is in a different region (us-east-1) but the S3 object is in another region, causing cross-region access which is not allowed by default. However, the most likely reason based on typical exam scenarios is that the S3 bucket policy does not grant the necessary S3 permissions.
What should I do if I get this DEA-C01 question wrong?
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.
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?
Standard ACLs match source addresses.
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