- A
Set the maximum retry count to 5 and configure a dead-letter queue on the Lambda function to capture failed records after retries.
Why wrong: Lambda's built-in DLQ is for asynchronous invocations, not for Kinesis event source mappings. Need a custom destination.
- B
Switch to using Amazon Kinesis Data Firehose to buffer data and use AWS Lambda for transformation with built-in retry logic.
Why wrong: Firehose does not provide per-record processing and may introduce latency.
- C
Set the maximum retry count to 5, configure an on-failure destination Amazon SQS queue, and set up a dead-letter queue on that SQS queue for poison pills.
This provides retries and isolates poison pills without blocking the main stream.
- D
Reduce the batch size to 1 and increase the Lambda function timeout to handle transient errors.
Why wrong: Reducing batch size may cause throttling and does not handle poison pills.
Quick Answer
The correct combination is to set the maximum retry count to 5, configure an on-failure destination Amazon SQS queue, and set up a dead-letter queue on that SQS queue for poison pills. This works because increasing retries allows Lambda to handle transient errors in Kinesis processing, while the SQS dead-letter queue isolates poison pill records that would otherwise block the entire batch. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your understanding of Lambda error handling with streaming sources—a common trap is thinking a DLQ alone suffices without enabling retries, or that reducing batch size addresses the root cause. Remember the key chain: Kinesis triggers Lambda, Lambda retries failed batches, and any records that exhaust retries go to an SQS DLQ for separate analysis. A useful memory tip is "Retry first, then poison pill to SQS DLQ"—this ensures no data loss while keeping the pipeline moving.
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.
A data engineering team is building a real-time data pipeline using Amazon Kinesis Data Streams with AWS Lambda for processing. The pipeline ingests clickstream data from a mobile app. The team notices that occasionally, a Lambda function fails due to a transient error, and the failed record is not retried, leading to data loss. The Lambda function is configured with a batch size of 100 and a maximum retry count of 0. The team wants to ensure that all records are processed successfully, even if transient failures occur. They also want to minimize the impact of poison pill records that could block processing. Which combination of actions should the team take to address this issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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
Set the maximum retry count to 5, configure an on-failure destination Amazon SQS queue, and set up a dead-letter queue on that SQS queue for poison pills.
Option B is correct because increasing the maximum retry count allows Lambda to retry failed batches, and splitting the failure destination into a separate SQS queue with a dead-letter queue (DLQ) for poison pills ensures that problematic records are isolated and can be analyzed separately, while the main processing continues. Option A is incorrect because using a DLQ alone without retries will still lose records if retries are not enabled. Option C is incorrect because reducing batch size may help but does not solve the retry or poison pill problem. Option D is incorrect because Kinesis Data Firehose is not suitable for real-time per-record processing.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Set the maximum retry count to 5 and configure a dead-letter queue on the Lambda function to capture failed records after retries.
Why it's wrong here
Lambda's built-in DLQ is for asynchronous invocations, not for Kinesis event source mappings. Need a custom destination.
- ✗
Switch to using Amazon Kinesis Data Firehose to buffer data and use AWS Lambda for transformation with built-in retry logic.
Why it's wrong here
Firehose does not provide per-record processing and may introduce latency.
- ✓
Set the maximum retry count to 5, configure an on-failure destination Amazon SQS queue, and set up a dead-letter queue on that SQS queue for poison pills.
Why this is correct
This provides retries and isolates poison pills without blocking the main stream.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
Reduce the batch size to 1 and increase the Lambda function timeout to handle transient errors.
Why it's wrong here
Reducing batch size may cause throttling and does not handle poison pills.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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. NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated. 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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related MLS-C01 NAT questions on configuration and troubleshooting.
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FAQ
Questions learners often ask
What does this MLS-C01 question test?
Data Engineering — This question tests Data Engineering — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Set the maximum retry count to 5, configure an on-failure destination Amazon SQS queue, and set up a dead-letter queue on that SQS queue for poison pills. — Option B is correct because increasing the maximum retry count allows Lambda to retry failed batches, and splitting the failure destination into a separate SQS queue with a dead-letter queue (DLQ) for poison pills ensures that problematic records are isolated and can be analyzed separately, while the main processing continues. Option A is incorrect because using a DLQ alone without retries will still lose records if retries are not enabled. Option C is incorrect because reducing batch size may help but does not solve the retry or poison pill problem. Option D is incorrect because Kinesis Data Firehose is not suitable for real-time per-record processing.
What should I do if I get this MLS-C01 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related MLS-C01 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 20, 2026
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.
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