- A
Increase the number of shards in the Kinesis stream to 20 and increase Lambda concurrency to 10.
Why wrong: Increasing shards without enough concurrency still causes throttling. Concurrency should be at least 2 per shard.
- B
Increase Lambda concurrency to at least 20 and reduce the batch size to 10.
More concurrency reduces throttling; smaller batch size reduces processing time per invocation.
- C
Disable the reserved concurrency limit on the Lambda function and decrease the batch size to 5.
Why wrong: Disabling concurrency limit could lead to uncontrolled scaling and potential issues.
- D
Increase the Lambda function timeout to 5 minutes and increase the batch size to 500.
Why wrong: Larger batch size increases processing time, worsening timeouts. Increasing timeout alone doesn't address throttling.
Lambda Concurrency and Kinesis Stream Throttling — Troubleshooting Timeouts
This DVA-C02 practice question tests your understanding of development with aws services. 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 a production application running on AWS Lambda that processes real-time streaming data from Amazon Kinesis Data Streams. The Lambda function is configured with a batch size of 100 and a maximum concurrency of 5. Recently, the application has been experiencing failures with a high number of invocation errors. The errors indicate that the function is timing out. The developer checks the CloudWatch metrics and notices that the IteratorAge metric for the Kinesis stream is increasing rapidly, and there are many Throttles events for the Lambda function. The average execution duration of the function is 30 seconds, and the function timeout is set to 1 minute. The Kinesis stream has 10 shards. The company expects the data volume to double in the next month. Which combination of actions should the developer take to resolve the issue and prepare for future growth?
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 Lambda concurrency to at least 20 and reduce the batch size to 10.
Option B is correct. The Lambda function is throttled because the maximum concurrency of 5 is too low for 10 shards. With a batch size of 100 and average duration of 30 seconds, each batch takes too long, leading to timeouts and increasing IteratorAge. Increasing concurrency to at least 20 (2 per shard) allows processing of all shards in parallel. Reducing batch size to 10 reduces the processing time per batch, helping avoid timeouts. Option A is wrong because increasing shards without increasing concurrency would worsen throttling. Option C is wrong because disabling reserved concurrency could lead to uncontrolled scaling, but the main issue is concurrency and batch size; also decreasing batch size to 5 may be too small and inefficient. Option D is wrong because increasing timeout and batch size would not resolve throttling and would increase latency.
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 number of shards in the Kinesis stream to 20 and increase Lambda concurrency to 10.
Why it's wrong here
Increasing shards without enough concurrency still causes throttling. Concurrency should be at least 2 per shard.
- ✓
Increase Lambda concurrency to at least 20 and reduce the batch size to 10.
Why this is correct
More concurrency reduces throttling; smaller batch size reduces processing time per invocation.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Disable the reserved concurrency limit on the Lambda function and decrease the batch size to 5.
Why it's wrong here
Disabling concurrency limit could lead to uncontrolled scaling and potential issues.
- ✗
Increase the Lambda function timeout to 5 minutes and increase the batch size to 500.
Why it's wrong here
Larger batch size increases processing time, worsening timeouts. Increasing timeout alone doesn't address throttling.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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.
Visual reference
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
What to study next
Got this wrong? Here's your next step.
Identify which DVA-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase Lambda concurrency to at least 20 and reduce the batch size to 10. — Option B is correct. The Lambda function is throttled because the maximum concurrency of 5 is too low for 10 shards. With a batch size of 100 and average duration of 30 seconds, each batch takes too long, leading to timeouts and increasing IteratorAge. Increasing concurrency to at least 20 (2 per shard) allows processing of all shards in parallel. Reducing batch size to 10 reduces the processing time per batch, helping avoid timeouts. Option A is wrong because increasing shards without increasing concurrency would worsen throttling. Option C is wrong because disabling reserved concurrency could lead to uncontrolled scaling, but the main issue is concurrency and batch size; also decreasing batch size to 5 may be too small and inefficient. Option D is wrong because increasing timeout and batch size would not resolve throttling and would increase latency.
What should I do if I get this DVA-C02 question wrong?
Identify which DVA-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 20, 2026
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