- A
Increase the number of shards in the stream
More shards increase the total read capacity.
- B
Decrease the data retention period
Why wrong: Retention period does not affect consumer speed.
- C
Use an AWS Lambda function to process the data
Why wrong: Lambda may still throttle if shard limits are hit.
- D
Enable enhanced fan-out on the stream
Enhanced fan-out provides dedicated throughput per consumer.
- E
Switch to the Kinesis Client Library (KCL)
Why wrong: KCL is a library, not a performance improvement by itself.
Question 454 of 1,755
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 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 number of shards in the stream
Increasing the number of shards in the stream directly increases the total read capacity of the Kinesis Data Stream. Each shard provides a fixed read throughput of 2 MB/s (or 5 read transactions per second), so adding shards allows the consumer fleet to parallelize processing across more data partitions, reducing the backlog and shard iterator age.
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
The trap here is that candidates often confuse 'switching to KCL' (a library) with a performance fix, when in fact KCL is just a helper for checkpointing and load balancing, not a throughput booster.
Detailed technical explanation
How to think about this question
Enhanced fan-out (option D) provides each consumer with its own dedicated 2 MB/s read throughput per shard, eliminating contention between consumers and reducing latency. Under the hood, it uses HTTP/2 server-push to deliver records directly to the consumer, bypassing the shared 2 MB/s per shard limit of the standard polling model. In real-world scenarios with multiple consumers or high-throughput streams, enabling enhanced fan-out can dramatically reduce iterator age without requiring shard scaling.
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 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.
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FAQ
Questions learners often ask
What does this MLS-C01 question test?
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 in the stream directly increases the total read capacity of the Kinesis Data Stream. Each shard provides a fixed read throughput of 2 MB/s (or 5 read transactions per second), so adding shards allows the consumer fleet to parallelize processing across more data partitions, reducing the backlog and shard iterator age.
What should I do if I get this MLS-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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Last reviewed: Jul 4, 2026
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