- A
Increase the batch size of the SQS event source mapping
A larger batch size means fewer invocations for the same number of messages, reducing the peak concurrent executions and thus throttling.
- B
Increase the reserved concurrency of the Lambda function
Why wrong: This raises the ceiling, but the function is already being throttled at 100. Increasing reserved concurrency might help if the account limit allows, but it does not address the root cause of high invocation volume.
- C
Decrease the batch window of the event source mapping
Why wrong: A smaller batch window causes Lambda to poll more frequently, increasing invocations and likely worsening throttling.
- D
Add a dead-letter queue (DLQ) for the Lambda function
Why wrong: A DLQ captures messages that are not successfully processed, but does not reduce the number of invocations or throttling.
DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
An AWS Lambda function that processes messages from an SQS queue is experiencing throttling (TooManyRequestsException). The function has reserved concurrency set to 100. The SQS queue has a redrive policy configured with maxReceiveCount of 5. CloudWatch metrics show that the function's concurrent executions occasionally spike to 100, and throttling occurs. The function execution time averages 2 seconds. What is the most effective way to reduce throttling?
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 batch size of the SQS event source mapping
Increasing the batch size allows the Lambda function to process more messages per invocation, reducing the number of concurrent executions needed to handle the same message volume. Since the function already spikes to its reserved concurrency of 100, processing more messages per batch lowers the invocation rate and thus reduces throttling without requiring additional concurrency.
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 batch size of the SQS event source mapping
Why this is correct
A larger batch size means fewer invocations for the same number of messages, reducing the peak concurrent executions and thus throttling.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Increase the reserved concurrency of the Lambda function
Why it's wrong here
This raises the ceiling, but the function is already being throttled at 100. Increasing reserved concurrency might help if the account limit allows, but it does not address the root cause of high invocation volume.
- ✗
Decrease the batch window of the event source mapping
Why it's wrong here
A smaller batch window causes Lambda to poll more frequently, increasing invocations and likely worsening throttling.
- ✗
Add a dead-letter queue (DLQ) for the Lambda function
Why it's wrong here
A DLQ captures messages that are not successfully processed, but does not reduce the number of invocations or throttling.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume throttling is always solved by increasing reserved concurrency, but the question explicitly states the function already spikes to its limit, so the correct approach is to reduce the number of invocations by increasing the batch size.
Detailed technical explanation
How to think about this question
SQS event source mappings use long polling and batch processing; the default batch size is 10, but can be increased up to 10,000 (for standard queues) or 10 (for FIFO). With a 2-second average execution time, a larger batch size means each invocation handles more messages, reducing the number of concurrent executions needed to drain the queue. This is a common optimization when reserved concurrency is a bottleneck and the function can handle larger batches without exceeding the 15-minute timeout.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase the batch size of the SQS event source mapping — Increasing the batch size allows the Lambda function to process more messages per invocation, reducing the number of concurrent executions needed to handle the same message volume. Since the function already spikes to its reserved concurrency of 100, processing more messages per batch lowers the invocation rate and thus reduces throttling without requiring additional concurrency.
What should I do if I get this DVA-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.
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Last reviewed: Jun 11, 2026
This DVA-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 DVA-C02 exam.
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