DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. 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 Lambda function processing SQS messages is failing with concurrency errors. The function is configured with reserved concurrency of 5. The SQS queue has a batch size of 10. What is the most effective way to prevent throttling?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the reserved concurrency to a higher value.
Option C is correct because the function is throttling due to insufficient reserved concurrency. With a batch size of 10, each SQS batch triggers one invocation, but the function's reserved concurrency of 5 limits concurrent executions to 5. Increasing reserved concurrency allows more concurrent invocations to handle the SQS messages without throttling.
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.
✗
Reduce the batch size to 1 to spread out invocations.
Why it's wrong here
Reducing batch size increases number of invocations, worsening throttling.
✗
Increase the Lambda function memory to get more concurrency.
Why it's wrong here
Memory does not affect concurrency limit.
✓
Increase the reserved concurrency to a higher value.
Why this is correct
More reserved concurrency prevents throttling.
Related concept
Read the scenario before looking for a memorised answer.
✗
Set the SQS queue's concurrency limit to match the Lambda reserved concurrency.
Why it's wrong here
SQS does not have a concurrency setting.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse batch size with concurrency, thinking reducing batch size reduces load, but it actually increases invocation count and worsens throttling.
Detailed technical explanation
How to think about this question
Lambda's reserved concurrency acts as a hard limit on concurrent executions for a function. When SQS invokes Lambda, each batch of up to 10 messages counts as one invocation. If the function's reserved concurrency is 5 and the queue has many messages, Lambda will throttle after 5 concurrent invocations, causing messages to become visible again after the visibility timeout. Increasing reserved concurrency to match the expected load (e.g., 100) allows Lambda to scale and process messages without throttling.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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 reserved concurrency to a higher value. — Option C is correct because the function is throttling due to insufficient reserved concurrency. With a batch size of 10, each SQS batch triggers one invocation, but the function's reserved concurrency of 5 limits concurrent executions to 5. Increasing reserved concurrency allows more concurrent invocations to handle the SQS messages without throttling.
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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Question Discussion
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