DEA-C01 Data Ingestion and Transformation Practice Question
A company uses Amazon Kinesis Data Firehose to deliver streaming data to Amazon S3. The data is in JSON format. The delivery stream is configured with a buffer size of 5 MB and a buffer interval of 60 seconds. However, the data engineer notices that S3 objects are being created with sizes much smaller than 5 MB. What is a likely cause?
⚠ Common exam trap
A common mix-up: candidates assume the buffer size is a hard minimum that must be reached before delivery, but Firehose uses an 'or' condition between buffer size and buffer interval, so low data rate causes interval-based delivery of small objects.
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 incoming data rate is too low, causing the buffer interval to trigger before reaching the buffer size.
Kinesis Data Firehose delivers data to S3 when either the buffer size (5 MB) or the buffer interval (60 seconds) is reached, whichever occurs first. If the incoming data rate is low, the buffer interval will expire before accumulating 5 MB of data, resulting in smaller S3 objects.
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 data is being compressed before delivery, reducing object size.
Why it's wrong here
Compression is optional.
- ✓
The incoming data rate is too low, causing the buffer interval to trigger before reaching the buffer size.
Why this is correct
Buffer interval triggers first.
- ✗
The data transformation lambda is splitting records into smaller ones.
Why it's wrong here
Not a typical behavior.
- ✗
The S3 bucket is configured with a lifecycle policy that splits objects.
Why it's wrong here
No such policy.
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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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.