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 and each record is about 2 KB. The delivery stream is configured to buffer data for 60 seconds or 5 MB, whichever comes first. The team notices that the S3 objects are very small (around 1 MB) and numerous, causing high costs due to S3 PUT requests. Which configuration change should the team make to reduce the number of S3 objects?
⚠ Common exam trap
Many candidates think reducing the buffer interval or enabling compression will reduce object count, but in reality, compression reduces object size (increasing count) and a shorter interval increases write frequency, both worsening the problem.
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
✓
Increase the buffer size to 50 MB and the buffer interval to 300 seconds.
Increasing the buffer size to 50 MB and the buffer interval to 300 seconds allows Kinesis Data Firehose to accumulate more data before writing to S3, resulting in fewer, larger objects. The current configuration triggers a write every 60 seconds or when 5 MB is buffered, but since each record is only 2 KB, the 5 MB threshold is rarely met, causing frequent small writes. By raising both thresholds, the delivery stream will buffer more records and write larger objects, reducing the number of S3 PUT requests and associated costs.
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 compression (GZIP) on the delivery stream.
Why it's wrong here
Compression reduces object size but not the number of objects; still many small objects.
- ✓
Increase the buffer size to 50 MB and the buffer interval to 300 seconds.
Why this is correct
Larger buffer accumulates more data before writing, resulting in fewer, larger objects.
- ✗
Reduce the buffer interval to 30 seconds and keep buffer size at 5 MB.
Why it's wrong here
Reducing interval creates more frequent, smaller objects, increasing costs.
- ✗
Switch from Kinesis Data Firehose to Amazon Kinesis Data Streams and use a Lambda function to write to S3.
Why it's wrong here
This is a different architecture; still would need batching logic to avoid many small objects.
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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Same concept, more angles
1 more way this is tested on DEA-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company uses Amazon Kinesis Data Firehose to deliver streaming data to an Amazon S3 bucket. The delivery occasionally fails due to 'ThrottlingException' from S3. What should the team do to resolve this issue without losing data?
medium- A.Enable S3 Transfer Acceleration on the destination bucket.
- B.Disable error logging in Firehose to reduce API calls.
- C.Configure Firehose to deliver data to Amazon DynamoDB instead.
- ✓ D.Increase the Firehose buffer size and buffer interval to reduce the number of S3 PUT requests.
Why D: The ThrottlingException from S3 indicates that Kinesis Data Firehose is sending too many PUT requests to S3. Increasing the buffer size or buffer interval causes Firehose to accumulate more records before writing, reducing the number of PUT requests and preventing throttling. Option A (S3 Transfer Acceleration) improves transfer speed, not request rate limits. Option B (disabling error logging) does not reduce API calls and hides issues. Option C (deliver to DynamoDB) is not supported by Kinesis Data Firehose. Therefore, option D is correct.
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.