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Question 350 of 507

Data Preparation for Machine Learning →hardMultiple ChoiceObjective-mapped

Quick Answer

The correct answer is to increase the buffer size to 10 MB and reduce the buffer interval to 60 seconds in the Firehose delivery stream configuration. This resolves the missing data problem because Kinesis Firehose only delivers a buffer window to S3 when either the buffer size or the buffer interval is reached first; when the last window at the end of the day contains fewer than 5 MB of data, the 5-minute interval never triggers a flush, leaving that final object undelivered. On the AWS Certified Machine Learning Engineer Associate MLA-C01 exam, this scenario tests your understanding of Firehose buffer mechanics and how they interact with time-based data pipelines—a common trap is assuming data loss or pipeline errors, when the real issue is an incomplete buffer window that never meets its flush condition. A useful memory tip is to think of Firehose as a timer and a scale: if the scale never fills, the timer must be shortened to force the delivery.

MLA-C01 Data Preparation for Machine Learning Practice Question

This MLA-C01 practice question tests your understanding of data preparation for machine learning. 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 operates an IoT platform that ingests sensor data from thousands of devices. Data is streamed via Amazon Kinesis Data Streams and stored in an S3 bucket using a Kinesis Firehose delivery stream, which writes data in 5-minute windows. The data is then used to train a machine learning model for anomaly detection. Recently, the data science team noticed that the training dataset is always missing the last 5 minutes of events from the end of each day. The S3 objects show that the last delivery stream buffer window is incomplete. The data engineer checked the Kinesis Firehose metrics and found no delivery errors or data loss, but the 'IncomingBytes' and 'IncomingRecords' metrics show consistent data for all periods. The S3 bucket has Lifecycle policies that do not delete objects. The team suspects the issue is related to the data preparation pipeline. Which course of action would correctly resolve the missing data problem?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "always"
Why it matters: Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.

Question 1hardmultiple choice

Full question →

A
Increase the buffer size to 10 MB and reduce the buffer interval to 60 seconds in the Firehose delivery stream configuration
Reducing the buffer interval to 60 seconds ensures that data is flushed every minute, preventing incomplete windows from being missed at the end of the day.
B
Reprocess the Kinesis stream data from the beginning using a custom application
Why wrong: Reprocessing does not address the root cause of incomplete buffer windows.
C
Modify the data preparation pipeline to use AWS Lambda to write data to S3 directly from Kinesis
Why wrong: This is a significant architectural change and not necessary; the issue is easily fixed by adjusting Firehose settings.
D
Increase the buffer interval to 600 seconds to allow more time for data to accumulate
Why wrong: Increasing the buffer interval would make the problem worse by delaying flushes further.

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

✓

Increase the buffer size to 10 MB and reduce the buffer interval to 60 seconds in the Firehose delivery stream configuration

Option A is correct because the issue is that the last 5-minute buffer window at the end of each day never completes, so Firehose never delivers that final object to S3. By reducing the buffer interval to 60 seconds and increasing the buffer size to 10 MB, Firehose will flush data more frequently, ensuring that even small residual data at the end of the day is delivered before the stream stops. This directly addresses the incomplete last window without requiring reprocessing or changing the pipeline architecture.

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 and reduce the buffer interval to 60 seconds in the Firehose delivery stream configuration
Why this is correct
Reducing the buffer interval to 60 seconds ensures that data is flushed every minute, preventing incomplete windows from being missed at the end of the day.
Clue confirmation
The clue word "always" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Reprocess the Kinesis stream data from the beginning using a custom application
Why it's wrong here
Reprocessing does not address the root cause of incomplete buffer windows.
✗
Modify the data preparation pipeline to use AWS Lambda to write data to S3 directly from Kinesis
Why it's wrong here
This is a significant architectural change and not necessary; the issue is easily fixed by adjusting Firehose settings.
✗
Increase the buffer interval to 600 seconds to allow more time for data to accumulate
Why it's wrong here
Increasing the buffer interval would make the problem worse by delaying flushes further.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates assume the missing data is due to data loss or pipeline errors, but the real issue is that Firehose's buffer window never completes when data stops arriving, so no S3 object is created for that final period.

Detailed technical explanation

How to think about this question

Kinesis Firehose uses a buffer interval (default 300 seconds) and a buffer size (default 5 MB) as two independent conditions; whichever is met first triggers a delivery. When data stops arriving at the end of a day, the buffer interval timer may never expire if the stream is idle, leaving the last partial buffer undelivered. By lowering the buffer interval to 60 seconds, Firehose will force a flush even with minimal data, ensuring the final window completes. This is a common pattern for time-bounded ingestion where data flow is not continuous.

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

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FAQ

Questions learners often ask

What does this MLA-C01 question test?

Data Preparation for Machine Learning — This question tests Data Preparation for Machine Learning — 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 and reduce the buffer interval to 60 seconds in the Firehose delivery stream configuration — Option A is correct because the issue is that the last 5-minute buffer window at the end of each day never completes, so Firehose never delivers that final object to S3. By reducing the buffer interval to 60 seconds and increasing the buffer size to 10 MB, Firehose will flush data more frequently, ensuring that even small residual data at the end of the day is delivered before the stream stops. This directly addresses the incomplete last window without requiring reprocessing or changing the pipeline architecture.

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

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

Are there clue words in this question I should notice?

Yes — watch for: "always". Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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