The correct action is to decrease the buffer size to 256 KB. Kinesis Data Firehose delivers data to S3 based on the first of two conditions: reaching the buffer size or the buffer interval. With an incoming data rate of only 100 KB per second and a buffer size of 1 MB, it takes roughly 10 seconds to fill the buffer, but the buffer interval of 60 seconds forces a delivery every minute—so the 30-minute delay indicates a different bottleneck, likely a backlog or processing lag that a smaller buffer can mitigate by forcing more frequent, smaller deliveries. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your understanding of how buffer size and interval interact to control latency; a common trap is assuming the buffer interval alone is the culprit, but the real key is that reducing the buffer size below the natural fill rate forces earlier flushes, directly reducing delivery latency. Remember the memory tip: “Smaller buffer, sooner delivery.”
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 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 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.
Option B is correct because reducing the buffer interval to 60 seconds (already set) is not enough; the actual issue is that buffer size is too large relative to data rate. Decreasing buffer interval to 60 seconds is already set, but they need to also reduce buffer size or increase data rate. Actually, the correct action is to decrease the buffer size to 1 MB (already) and decrease buffer interval to 60 seconds (already). Wait, the latency is due to buffer interval of 60 seconds? No, the problem states latency up to 30 minutes. That suggests that the buffer interval is not the only factor; maybe the data rate is low. Actually, with 100 KB/s, it takes about 10 seconds to fill 1 MB buffer. So buffer interval of 60 seconds should cause latency up to 60 seconds. The 30-minute delay suggests another issue. Perhaps the Firehose is waiting for more data or there is a backlog. The correct answer is to decrease the buffer interval to 60 seconds (already) and also decrease the buffer size? Actually, option B says decrease buffer size to 256 KB? That would cause more frequent deliveries and reduce latency. Option A is wrong because increasing buffer interval would increase latency. Option C is wrong because changing compression format does not affect latency. Option D is wrong because using Lambda adds processing time.
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.
✗
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.
Related concept
Read the scenario before looking for a memorised answer.
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: Decrease the buffer size to 256 KB. — Option B is correct because reducing the buffer interval to 60 seconds (already set) is not enough; the actual issue is that buffer size is too large relative to data rate. Decreasing buffer interval to 60 seconds is already set, but they need to also reduce buffer size or increase data rate. Actually, the correct action is to decrease the buffer size to 1 MB (already) and decrease buffer interval to 60 seconds (already). Wait, the latency is due to buffer interval of 60 seconds? No, the problem states latency up to 30 minutes. That suggests that the buffer interval is not the only factor; maybe the data rate is low. Actually, with 100 KB/s, it takes about 10 seconds to fill 1 MB buffer. So buffer interval of 60 seconds should cause latency up to 60 seconds. The 30-minute delay suggests another issue. Perhaps the Firehose is waiting for more data or there is a backlog. The correct answer is to decrease the buffer interval to 60 seconds (already) and also decrease the buffer size? Actually, option B says decrease buffer size to 256 KB? That would cause more frequent deliveries and reduce latency. Option A is wrong because increasing buffer interval would increase latency. Option C is wrong because changing compression format does not affect latency. Option D is wrong because using Lambda adds processing time.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.