← DEA-C01·Amazon Web Services

Question 1,014 of 1,786

Data Ingestion and Transformation →mediumMultiple ChoiceObjective-mapped

Decrease Kinesis Firehose Delivery Latency with Buffer Interval

This DEA-C01 practice question tests your understanding of data ingestion and transformation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 is ingesting log files from multiple EC2 instances into Amazon S3 using the CloudWatch agent. The logs are delivered to a CloudWatch Logs group, and a subscription filter sends them to a Lambda function for transformation, then to Firehose. The Firehose stream is configured with a buffer interval of 60 seconds and buffer size of 5 MB. The logs are critical and must be available in S3 within 5 minutes. What is the most cost-effective way to reduce the delivery latency?

A
Replace Firehose with Amazon Kinesis Data Streams
Why wrong: KDS adds cost and requires additional consumers.
B
Increase the buffer size to 10 MB
Why wrong: Larger buffer size increases latency.
C
Increase the buffer interval to 120 seconds
Why wrong: Increases latency.
D
Decrease the buffer interval to 10 seconds
Lower buffer interval reduces delivery latency.

Full breakdown with real-world context →

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 interval to 10 seconds

Decreasing the Firehose buffer interval to 10 seconds directly reduces the maximum time data waits in the buffer before being delivered to S3, ensuring logs reach S3 within the required 5-minute window. Since the current 60-second buffer interval is the primary contributor to latency, lowering it to 10 seconds minimizes delivery delay without incurring additional costs, as Firehose charges are based on data volume, not buffer frequency.

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.

✗
Replace Firehose with Amazon Kinesis Data Streams
Why it's wrong here
KDS adds cost and requires additional consumers.
✗
Increase the buffer size to 10 MB
Why it's wrong here
Larger buffer size increases latency.
✗
Increase the buffer interval to 120 seconds
Why it's wrong here
Increases latency.
✓
Decrease the buffer interval to 10 seconds
Why this is correct
Lower buffer interval reduces delivery latency.
Related concept
Read the scenario before looking for a memorised answer.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates may think increasing buffer size or interval improves throughput, but the question asks for reduced latency, so decreasing the buffer interval is the direct and cost-effective solution.

Detailed technical explanation

How to think about this question

Firehose uses buffer hints (interval and size) to batch records before delivery; the first condition met triggers the write. Decreasing the buffer interval to 10 seconds ensures data is flushed more frequently, but note that if the buffer size is reached sooner, the interval may not be the limiting factor. In high-volume scenarios, the 5 MB buffer size might already trigger delivery before the interval expires, so adjusting the interval is most effective for low-volume streams where the interval is the primary delay.

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.

TExam Day Tips

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 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.

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

What to study next

Got this wrong? Here's your next step.

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FAQ

Questions learners often ask

What does this DEA-C01 question test?

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 interval to 10 seconds — Decreasing the Firehose buffer interval to 10 seconds directly reduces the maximum time data waits in the buffer before being delivered to S3, ensuring logs reach S3 within the required 5-minute window. Since the current 60-second buffer interval is the primary contributor to latency, lowering it to 10 seconds minimizes delivery delay without incurring additional costs, as Firehose charges are based on data volume, not buffer frequency.

What should I do if I get this DEA-C01 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Same concept, more angles

1 more ways 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 ingests JSON logs into Amazon S3 using Kinesis Data Firehose. The logs contain a timestamp field, but the delivery to S3 is delayed by up to 15 minutes during peak hours. The business requires near-real-time availability (under 2 minutes). Which configuration change should the data engineer make?

medium

A.Increase the number of shards in the Kinesis Data Firehose stream
B.Increase the buffer size to 128 MB
✓ C.Decrease the buffer interval to 60 seconds
D.Enable buffering hints in the Firehose delivery stream

Why C: Option C is correct because decreasing the buffer interval to 60 seconds forces Kinesis Data Firehose to deliver data to S3 more frequently, reducing the maximum delivery latency to under 2 minutes. The default buffer interval is 300 seconds (5 minutes), and by lowering it to 60 seconds, you ensure that data is flushed to S3 within one minute of ingestion, meeting the near-real-time requirement even during peak hours when buffering might otherwise delay delivery.

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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.