The answer is to use provisioned concurrency for the Lambda function. This is correct because provisioned concurrency pre-warms a specified number of execution environments, eliminating the cold starts that cause high latency when processing Kinesis streams, even when the average invocation rate is low. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of how Lambda scales with stream-based triggers: a common trap is assuming that low average concurrency means no latency issues, but cold starts can still spike latency during batch processing. Provisioned concurrency directly addresses this by keeping environments initialized, ensuring the function is ready to handle sudden bursts from Kinesis without initialization overhead. Memory tip: think of provisioned concurrency as a "warm pool" for your Lambda—it keeps the engine running so you never wait for a cold start.
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 developer is troubleshooting an AWS Lambda function that processes streaming data from Amazon Kinesis Data Streams. The function processes records in batches. The developer notices that the function often experiences high latency even though the average invocation rate is well below the account concurrency limit. Which action would MOST effectively reduce latency?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use provisioned concurrency for the function.
Provisioned concurrency pre-warms a specified number of execution environments, eliminating cold starts and ensuring that the function can handle sudden bursts of traffic without latency spikes. Since the function processes streaming data from Kinesis and experiences high latency despite low average concurrency, the issue is likely cold starts or initialization overhead, which provisioned concurrency directly mitigates.
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 for the Kinesis event source mapping.
Why it's wrong here
Larger batch sizes may increase per-invocation workload and latency, and they do not address cold start delays.
✗
Enable reserved concurrency for the function.
Why it's wrong here
Reserved concurrency prevents other functions from using the allocation, but it does not pre-warm environments to reduce cold start time.
✗
Increase the number of shards in the Kinesis data stream.
Why it's wrong here
More shards increase parallelism but do not reduce latency for each individual Lambda invocation.
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse concurrency limits (reserved concurrency) with performance optimization, or assume that increasing shards or batch sizes will always reduce latency, when in fact the root cause is cold start latency that provisioned concurrency directly addresses.
Detailed technical explanation
How to think about this question
Provisioned concurrency works by keeping a specified number of execution environments initialized and ready to serve requests immediately, bypassing the cold start phase that can add 100ms to several seconds of latency. For Kinesis event source mappings, each shard is processed by one Lambda invocation at a time, so if the function has a long initialization (e.g., loading ML models or connecting to databases), provisioned concurrency ensures that the first invocation on each shard does not incur that delay. This is particularly effective when the stream has many shards but the overall invocation rate is low, as each shard's first invocation after idle time would otherwise be a cold start.
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: Use provisioned concurrency for the function. — Provisioned concurrency pre-warms a specified number of execution environments, eliminating cold starts and ensuring that the function can handle sudden bursts of traffic without latency spikes. Since the function processes streaming data from Kinesis and experiences high latency despite low average concurrency, the issue is likely cold starts or initialization overhead, which provisioned concurrency directly mitigates.
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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