The answer is to increase the buffer size to 10 MB. This is correct because Kinesis Data Firehose writes objects to S3 only when either the buffer size or the buffer interval is reached first; with a 5 MB buffer and a 2 MB/s ingestion rate, the 60-second interval triggers a write every minute, producing a 2 MB object instead of waiting to fill the buffer. To optimize buffering and avoid small S3 objects, you must raise the buffer size so that the size threshold is hit before the time interval, allowing larger, more cost-efficient objects. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of Firehose’s two triggering conditions—a common trap is to decrease the buffer interval, which would create even more small objects. Remember the memory tip: “Size before time” — always increase buffer size to reduce object count, never shorten the interval.
DEA-C01 Data Ingestion and Transformation Practice Question
This DEA-C01 practice question tests your understanding of data ingestion and transformation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A data engineer is troubleshooting a Kinesis Data Firehose delivery stream that sends data to an Amazon S3 bucket. The delivery stream has a buffer size of 5 MB and a buffer interval of 60 seconds. The data ingestion rate is 2 MB per second. The engineer notices that S3 objects are created every 60 seconds but each object is only about 2 MB. What should the engineer do to reduce the number of small S3 objects?
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 10 MB.
Option A is correct because increasing the buffer size to 10 MB will allow the stream to buffer more data before writing to S3, resulting in larger objects. Option B is wrong because decreasing the buffer interval would create objects more frequently, making the problem worse. Option C is wrong because switching to Kinesis Data Streams does not solve the buffering issue. Option D is wrong because reducing the buffer size would create even smaller objects.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Increase the buffer size to 10 MB.
Why this is correct
Larger buffer size means more data accumulates before an S3 write.
Related concept
Read the scenario before looking for a memorised answer.
✗
Decrease the buffer interval to 30 seconds.
Why it's wrong here
Shorter interval would create smaller objects.
✗
Reduce the buffer size to 2 MB.
Why it's wrong here
Smaller buffer size would create even smaller objects.
✗
Switch to Kinesis Data Streams and use a Lambda function to write to S3.
Why it's wrong here
This adds complexity and does not directly address buffering.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Data Ingestion and Transformation — This question tests Data Ingestion and Transformation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase the buffer size to 10 MB. — Option A is correct because increasing the buffer size to 10 MB will allow the stream to buffer more data before writing to S3, resulting in larger objects. Option B is wrong because decreasing the buffer interval would create objects more frequently, making the problem worse. Option C is wrong because switching to Kinesis Data Streams does not solve the buffering issue. Option D is wrong because reducing the buffer size would create even smaller objects.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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.
Question Discussion
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