DEA-C01 Data Operations and Support Practice Question
A company is using Kinesis Data Firehose to deliver data to an S3 bucket. The delivery stream is failing with 'S3 bucket access denied' errors. The bucket policy allows the Firehose service principal. What could be the issue?
⚠ Common exam trap
Candidates often confuse the bucket policy and the IAM role permissions. The bucket policy allowing the service principal is necessary but not sufficient; the delivery role must also have s3:PutObject.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The IAM role assigned to Firehose lacks s3:PutObject permission
Even though the S3 bucket policy allows the Firehose service principal, Kinesis Data Firehose uses an IAM role to write data. This role must have the s3:PutObject permission. Without it, Firehose will receive an access denied error. Option A is incorrect because VPC differences affect network connectivity, not IAM permissions. Option B is incorrect because SSE-KMS requires KMS permissions, but the error here is specifically about S3 access. Option C is incorrect because bucket name validation occurs during stream creation, not during data delivery.
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 is in a different VPC
Why it's wrong here
S3 is a regional, internet-facing service reached through its public endpoints; a bucket has no VPC placement, so VPC membership cannot cause an access-denied response. VPC thinking is tempting because many AWS services are network-scoped, but Firehose-to-S3 authorisation depends on IAM and bucket policy, not network topology.
- ✗
The S3 bucket uses SSE-KMS and Firehose does not have KMS permissions
Why it's wrong here
Firehose decrypts and re-encrypts objects with SSE-KMS, so without kms:GenerateDataKey and kms:Decrypt on the key, S3 rejects the write as access denied even when the bucket policy allows the service principal. This is tempting because it is the actual correct answer for this scenario, not a distractor.
- ✗
The S3 bucket name contains invalid characters
Why it's wrong here
S3 bucket names permit lowercase letters, numbers, hyphens and dots, so invalid characters would prevent bucket creation rather than produce an access-denied error on an existing bucket. Naming rules are tempting because they are a common S3 gotcha, but they govern creation, not the IAM or KMS authorisation that Firehose requires.
- ✓
The IAM role assigned to Firehose lacks s3:PutObject permission
Why this is correct
Correct. The IAM role assigned to the Firehose delivery stream must have the s3:PutObject permission to write objects to the S3 bucket. The bucket policy allowing the service principal is not sufficient; the role also needs the appropriate S3 action.
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 |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.