DEA-C01 Data Ingestion and Transformation Practice Question
A company has a Kinesis Data Firehose delivery stream that receives JSON data from IoT devices. The data is delivered to an S3 bucket. The company notices that the data in S3 is delayed by up to 30 minutes. The Firehose stream is configured with a buffer size of 1 MB and a buffer interval of 60 seconds. The incoming data rate is approximately 100 KB per second. The company needs to reduce the delivery latency to under 5 minutes. Which action should the company take?
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
✓
Decrease the buffer size to 256 KB.
The observed latency of up to 30 minutes is likely due to the buffer size being too large relative to the data rate, causing long waits to fill the buffer. With a data rate of 100 KB/s and a buffer size of 1 MB, the buffer fills in approximately 10 seconds, but the buffer interval of 60 seconds already limits delivery to at most 60 seconds. However, the 30-minute delay suggests additional issues such as backlog or configuration errors. Decreasing the buffer size to 256 KB will cause more frequent deliveries (every ~2.5 seconds), reducing latency. Option A (Lambda transformation) adds processing time and increases latency. Option B (increase buffer interval to 300 seconds) would increase latency. Option C (change compression) does not affect delivery frequency. Therefore, option D is correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Enable Lambda transformation to process data faster.
Why it's wrong here
Lambda transformation adds processing time, increasing latency.
- ✗
Increase the buffer interval to 300 seconds.
Why it's wrong here
Increasing buffer interval would increase latency.
- ✗
Change the compression format from GZIP to Snappy.
Why it's wrong here
Compression does not significantly affect delivery latency.
- ✓
Decrease the buffer size to 256 KB.
Why this is correct
Smaller buffer size causes more frequent deliveries, reducing latency.
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.