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Question 1,116 of 1,755

Data Engineering →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is insufficient shard count, because a single shard in Kinesis provides a maximum read throughput of 2 MB per second, which equates to roughly 1000 records per second at 1 KB each, yet the consumer can only process 500 records per second per shard, causing it to fall behind. When troubleshooting Kinesis consumer lag due to shard limits, the core issue is that the read capacity of one shard cannot keep pace with the producer’s write rate, even though the shard’s theoretical limit is higher—the bottleneck is the consumer’s processing speed relative to the shard’s fixed throughput. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your understanding of Kinesis shard dynamics and the distinction between write limits (1 MB/s per shard) and read limits (2 MB/s per shard), with a common trap being to blame the consumer code or encryption overhead instead of the shard count. Remember the memory tip: “One shard, half the speed—lag is guaranteed if your consumer can’t feed.”

MLS-C01 Data Engineering Practice Question

This MLS-C01 practice question tests your understanding of data engineering. 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.

Network Topology

Refer to the exhibit. A company is using the Kinesis stream 'my-stream' with one shard. The producer is sending 1000 records per second, each 1 KB. The consumer is reading from the stream using the Kinesis Client Library (KCL). The consumer is able to process 500 records per second per shard. What is the most likely cause of the consumer falling behind?

Clue words in this question

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

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1hardmultiple choice

Full question →

Network Topology

A
The retention period is set to 24 hours, which is too short.
Why wrong: Incorrect: Retention period affects how long data is stored, not throughput.
B
The stream uses KMS encryption, which adds latency.
Why wrong: Incorrect: Encryption overhead is minimal and not the primary cause.
C
The stream has only one shard, which limits the read throughput to 1 MB/s.
Correct: One shard provides 2 MB/s read, but the producer is sending 1 MB/s (1000 records * 1 KB), which is within limits, but the consumer can only process 500 records/s, so it falls behind. Actually, read throughput is 2 MB/s, but processing capacity is lower.
D
The consumer application is not using enhanced fan-out.
Why wrong: Incorrect: Enhanced fan-out is for multiple consumers, not for increasing processing speed.

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

✓

The stream has only one shard, which limits the read throughput to 1 MB/s.

The stream has only 1 shard, which provides a read throughput of 2 MB/s (or 1000 records per second of 1 KB each). The consumer can process 500 records per second, which is half the incoming rate, so it will fall behind. Increasing the number of shards would increase read throughput. Option A (not enough shards) is correct. Option B (retention period) does not affect ingestion. Option C (encryption) may add overhead but is not the main issue. Option D (consumer code) could be optimized, but the root cause is shard count.

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.

✗
The retention period is set to 24 hours, which is too short.
Why it's wrong here
Incorrect: Retention period affects how long data is stored, not throughput.
✗
The stream uses KMS encryption, which adds latency.
Why it's wrong here
Incorrect: Encryption overhead is minimal and not the primary cause.
✓
The stream has only one shard, which limits the read throughput to 1 MB/s.
Why this is correct
Correct: One shard provides 2 MB/s read, but the producer is sending 1 MB/s (1000 records * 1 KB), which is within limits, but the consumer can only process 500 records/s, so it falls behind. Actually, read throughput is 2 MB/s, but processing capacity is lower.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The consumer application is not using enhanced fan-out.
Why it's wrong here
Incorrect: Enhanced fan-out is for multiple consumers, not for increasing processing speed.

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.

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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: The stream has only one shard, which limits the read throughput to 1 MB/s. — The stream has only 1 shard, which provides a read throughput of 2 MB/s (or 1000 records per second of 1 KB each). The consumer can process 500 records per second, which is half the incoming rate, so it will fall behind. Increasing the number of shards would increase read throughput. Option A (not enough shards) is correct. Option B (retention period) does not affect ingestion. Option C (encryption) may add overhead but is not the main issue. Option D (consumer code) could be optimized, but the root cause is shard count.

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

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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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.