DEA-C01 Data Ingestion and Transformation Practice Question
A company is using Amazon Kinesis Data Firehose to deliver streaming data to an S3 bucket. The data includes a timestamp field. They want to partition the S3 objects by hour dynamically. The Firehose delivery stream is configured with a prefix like 'year=!{timestamp:yyyy}/month=!{timestamp:MM}/day=!{timestamp:dd}/hour=!{timestamp:HH}/'. However, the objects are not being partitioned as expected; all files end up in a single partition. What is the MOST likely cause?
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
✓
Dynamic partitioning is not enabled in the Firehose delivery stream configuration.
Amazon Kinesis Data Firehose requires dynamic partitioning to be explicitly enabled in the delivery stream configuration in order to use custom partitioning keys and create partition prefixes dynamically. Without enabling dynamic partitioning, the timestamp expressions in the prefix are treated as static strings, resulting in a single partition. Option B is incorrect because buffer size affects delivery frequency, not partitioning behavior; even with large buffers, partitioning would still occur if dynamic partitioning were enabled. Option C is incorrect because time zone differences would cause incorrect hours, not a single partition; all files would still be distributed across hours. Option D is incorrect because IAM permission issues would cause write failures, not mispartitioning; the objects would simply not be delivered.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Dynamic partitioning is not enabled in the Firehose delivery stream configuration.
Why this is correct
Without enabling dynamic partitioning, the prefix is static and all data goes into one S3 prefix.
- ✗
The buffer size is set too large, delaying file delivery.
Why it's wrong here
Buffer size affects how often files are written, not partitioning.
- ✗
The timestamp is in UTC but the prefix uses local time.
Why it's wrong here
Time zone mismatch would produce wrong hour, not a single partition.
- ✗
The IAM role for Firehose lacks permissions to write to S3 with dynamic prefixes.
Why it's wrong here
Lack of permissions would cause errors, not mispartitioning.
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.