The correct actions are to increase the number of shards and enable enhanced fan-out on the stream. Increasing shards directly boosts the stream’s ingestion parallelism, allowing the consumer fleet to process more data records concurrently, which reduces the shard iterator age. Enhanced fan-out provides each consumer with its own dedicated read throughput of 2 MB per second per shard, eliminating the contention that occurs with the default shared throughput of 5 transactions per second per shard. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your understanding of Kinesis Data Streams consumer lag solutions, often appearing as a multi-select question where you must distinguish between scaling the stream and tuning the consumer. A common trap is confusing retention period changes with performance fixes—retention only affects data availability, not throughput. Memory tip: think “more shards for more speed, enhanced fan-out for no competition.”
MLS-C01 Data Engineering Practice Question
This MLS-C01 practice question tests your understanding of data engineering. 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 company is using Amazon Kinesis Data Streams to ingest clickstream data. The data is consumed by a fleet of EC2 instances running a custom consumer application. The consumer is falling behind and the shard iterator age is increasing. Which TWO actions should the data engineer take to improve consumer performance? (Choose TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the number of shards in the stream
Increasing the number of shards increases parallelism, and using enhanced fan-out allows each consumer to have its own read throughput. Option B is wrong because decreasing retention period does not improve consumer performance. Option D is wrong because using a Lambda function may not help if the bottleneck is shard throughput. Option E is wrong because using KCL (Kinesis Client Library) is already standard; not a direct fix.
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 number of shards in the stream
Why this is correct
More shards increase the total read capacity.
Related concept
Read the scenario before looking for a memorised answer.
✗
Decrease the data retention period
Why it's wrong here
Retention period does not affect consumer speed.
✗
Use an AWS Lambda function to process the data
Why it's wrong here
Lambda may still throttle if shard limits are hit.
✓
Enable enhanced fan-out on the stream
Why this is correct
Enhanced fan-out provides dedicated throughput per consumer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Switch to the Kinesis Client Library (KCL)
Why it's wrong here
KCL is a library, not a performance improvement by itself.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which MLS-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 Engineering — This question tests Data Engineering — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase the number of shards in the stream — Increasing the number of shards increases parallelism, and using enhanced fan-out allows each consumer to have its own read throughput. Option B is wrong because decreasing retention period does not improve consumer performance. Option D is wrong because using a Lambda function may not help if the bottleneck is shard throughput. Option E is wrong because using KCL (Kinesis Client Library) is already standard; not a direct fix.
What should I do if I get this MLS-C01 question wrong?
Identify which MLS-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 →
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 uses Amazon Kinesis Data Streams to collect IoT sensor data. The stream has 4 shards. A consumer application reads from the stream using the Kinesis Client Library (KCL). The application processes records and stores them in Amazon DynamoDB. Recently, the data volume has increased, and the consumer is falling behind. Which action should the team take to increase the processing throughput?
medium
A.Deploy additional consumer instances using the same application name.
B.Increase the write capacity of the DynamoDB table.
C.Increase the data retention period of the stream to 7 days.
✓ D.Increase the number of shards in the Kinesis stream.
Why D: Option C is correct because increasing the number of shards increases the stream's throughput and allows more concurrent consumers. Option A is wrong because increasing the retention period does not affect throughput. Option B is wrong because adding more KCL workers without increasing shards will cause them to idle. Option D is wrong because increasing DynamoDB write capacity may reduce throttling but does not increase the consumer's reading throughput.
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This MLS-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 MLS-C01 exam.
Question Discussion
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