The answer is to increase the Firehose buffering interval to 300 seconds and buffering size to 64 MB. This directly addresses the root cause of small files by forcing Kinesis Data Firehose to accumulate more data before writing to S3, batching records into fewer, larger objects that reduce downstream processing overhead. On the AWS Certified Data Engineer Associate DEA-C01 exam, this concept tests your understanding of Firehose’s delivery optimization parameters—a common trap is choosing a serverless Lambda aggregation, which adds cost and complexity without preventing the small files at the source. Remember, Firehose’s native buffering controls are the most efficient lever; think “buffer big, batch better” to avoid the distraction of post-delivery fixes like Glue ETL.
DEA-C01 Data Ingestion and Transformation Practice Question
This DEA-C01 practice question tests your understanding of data ingestion and transformation. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 pipeline ingests streaming data from Kinesis Data Streams into S3 via Kinesis Data Firehose. Occasionally, small files are written to S3, increasing downstream processing costs. What is the most efficient way to reduce the number of small files?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the Firehose buffering interval to 300 seconds and buffering size to 64 MB.
Option C is correct because increasing the buffering interval and size in Firehose batches more data into fewer files. Option A is wrong because Lambda can aggregate but adds complexity and cost. Option B is wrong because KCL runs on EC2, not serverless. Option D is wrong because Glue ETL runs after delivery, not preventing small files.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use a Lambda function to aggregate records before sending to Firehose.
Why it's wrong here
Adds complexity and cost; Firehose buffering is simpler.
✗
Use the Kinesis Client Library (KCL) to write larger batches to S3 directly.
Why it's wrong here
Requires managing EC2 instances.
✗
Run a daily AWS Glue job to concatenate small files.
Why it's wrong here
Does not prevent small files; adds extra compute.
✓
Increase the Firehose buffering interval to 300 seconds and buffering size to 64 MB.
Why this is correct
Firehose will buffer more data per file.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
Data Ingestion and Transformation — This question tests Data Ingestion and Transformation — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Increase the Firehose buffering interval to 300 seconds and buffering size to 64 MB. — Option C is correct because increasing the buffering interval and size in Firehose batches more data into fewer files. Option A is wrong because Lambda can aggregate but adds complexity and cost. Option B is wrong because KCL runs on EC2, not serverless. Option D is wrong because Glue ETL runs after delivery, not preventing small files.
What should I do if I get this DEA-C01 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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.