The correct answer is to implement reportBatchItemFailures in the Lambda function and enable partial batch response for the SQS event source mapping. This approach directly addresses Lambda SQS partial batch failure handling by allowing the function to return a list of failed message IDs, so only those specific messages are retried instead of the entire batch of ten. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of event source mapping configurations and the difference between standard retry behavior and partial batch responses. A common trap is assuming that reducing the batch size or increasing retries solves the problem, but those approaches waste throughput and delay processing of successful messages. The key insight is that without reportBatchItemFailures, a single failure causes the whole batch to be retried or sent to the dead-letter queue, which is inefficient. Memory tip: think “report the failures, not the whole batch” — the function reports which items failed, and SQS retries only those.
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. 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 has an AWS Lambda function that processes messages from an Amazon SQS queue. The function is invoked with a batch size of 10. Some messages are failing repeatedly, causing the function to retry them up to the maximum retry count and then they are sent to a dead-letter queue (DLQ). The company wants to improve the resilience of the application by handling partial batch failures more efficiently. What should a solutions architect do?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement reportBatchItemFailures in the Lambda function and enable partial batch response for the SQS event source mapping.
Option B is correct because implementing reportBatchItemFailures in the Lambda function and enabling partial batch response for the SQS event source mapping allows the function to signal which specific messages within a batch failed. This prevents the entire batch from being retried or sent to the DLQ, and only the failed messages are retried individually, improving resilience and efficiency.
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.
✗
Move the messages to a DLQ immediately after the first failure.
Why it's wrong here
This would lose messages that could be retried successfully.
✓
Implement reportBatchItemFailures in the Lambda function and enable partial batch response for the SQS event source mapping.
Why this is correct
This allows Lambda to report individual failures so only those messages are retried.
Related concept
Read the scenario before looking for a memorised answer.
✗
Decrease the batch size to 1 so that each invocation processes a single message.
Why it's wrong here
This reduces throughput and does not handle partial failures in a batch.
✗
Increase the batch size to 100 to process more messages per invocation.
Why it's wrong here
This may increase the number of failures per invocation.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think decreasing batch size to 1 is the simplest fix, but that ignores the throughput impact and the fact that AWS provides a native partial batch failure mechanism that is more efficient and scalable.
Detailed technical explanation
How to think about this question
The reportBatchItemFailures feature works by having the Lambda function return a list of failed message IDs in its response. The SQS event source mapping then uses this list to mark only those messages as failed, leaving successful messages as processed. This mechanism relies on the function's response format and the event source mapping's 'FunctionResponseTypes' configuration, which must be set to 'ReportBatchItemFailures'. Under the hood, this reduces the number of invocations and DLQ writes, as only genuinely failed messages are retried.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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.
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement reportBatchItemFailures in the Lambda function and enable partial batch response for the SQS event source mapping. — Option B is correct because implementing reportBatchItemFailures in the Lambda function and enabling partial batch response for the SQS event source mapping allows the function to signal which specific messages within a batch failed. This prevents the entire batch from being retried or sent to the DLQ, and only the failed messages are retried individually, improving resilience and efficiency.
What should I do if I get this SAP-C02 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.
About these practice questions
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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 is using an AWS Lambda function to process records from an Amazon Kinesis stream. The function stores results in an Amazon DynamoDB table. The team notices that the Lambda function sometimes fails due to throttling from DynamoDB. Which TWO actions should the team take to improve the continuous processing of records? (Choose TWO.)
easy
A.Increase the number of shards in the Kinesis stream to reduce data per Lambda invocation.
B.Configure reserved concurrency for the Lambda function to limit its maximum concurrency.
C.Increase the concurrency limit for the Lambda function to allow more parallel executions.
✓ D.Switch the DynamoDB table to on-demand capacity mode.
✓ E.Enable DynamoDB auto scaling for the table to adjust read/write capacity automatically.
Why D: Option D is correct because switching the DynamoDB table to on-demand capacity mode eliminates the need to provision read/write capacity, allowing the table to automatically scale to handle any throttling caused by sudden spikes in Lambda writes. This directly addresses the throttling issue without requiring manual capacity management.
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This SAP-C02 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 SAP-C02 exam.
Question Discussion
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