- A
Enable API caching in API Gateway.
Why wrong: API caching reduces the number of requests that reach the backend for cached responses, but the 429 error occurs at the API Gateway level due to throttling limits, not backend capacity. This does not directly resolve the throttling issue.
- B
Enable DynamoDB auto-scaling.
Why wrong: DynamoDB auto-scaling adjusts read/write capacity based on usage, which helps if DynamoDB is throttling, but the 429 error originates from API Gateway, not DynamoDB. Not the direct solution.
- C
Increase the throttling limits in API Gateway.
Increasing API Gateway throttling limits directly allows more requests to be processed before hitting the limit. This is the most cost-effective as it involves only a configuration change without additional infrastructure costs.
- D
Increase the reserved concurrency of the Lambda function.
Why wrong: Increasing Lambda reserved concurrency ensures Lambda can handle more concurrent invocations, but the 429 error is from API Gateway exceeding its own limit, not from Lambda throttling. This would be more expensive and not address the root cause.
SAP-C02 API Gateway Throttling Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. A key principle to apply: aPI Gateway Throttling. 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 is using Amazon API Gateway to expose a REST API. The API backend is a Lambda function that queries an Amazon DynamoDB table. During peak hours, the API returns HTTP 429 (Too Many Requests) errors. What is the MOST cost-effective way to reduce these errors?
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 throttling limits in API Gateway.
The correct answer is C because HTTP 429 errors from API Gateway indicate that the request rate is exceeding the configured throttling limits. Increasing the throttling limits allows more requests to pass through directly, and this is a cost-effective configuration change. Option A (API caching) can reduce backend load but does not address the throttling limit itself. Option B (DynamoDB auto-scaling) addresses DynamoDB capacity, not API Gateway throttling. Option D (Lambda reserved concurrency) addresses Lambda throttling, but the 429 is from API Gateway, not Lambda.
Key principle: API Gateway Throttling
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Enable API caching in API Gateway.
Why it's wrong here
API caching reduces the number of requests that reach the backend for cached responses, but the 429 error occurs at the API Gateway level due to throttling limits, not backend capacity. This does not directly resolve the throttling issue.
- ✗
Enable DynamoDB auto-scaling.
Why it's wrong here
DynamoDB auto-scaling adjusts read/write capacity based on usage, which helps if DynamoDB is throttling, but the 429 error originates from API Gateway, not DynamoDB. Not the direct solution.
- ✓
Increase the throttling limits in API Gateway.
- ✗
Increase the reserved concurrency of the Lambda function.
Why it's wrong here
Increasing Lambda reserved concurrency ensures Lambda can handle more concurrent invocations, but the 429 error is from API Gateway exceeding its own limit, not from Lambda throttling. This would be more expensive and not address the root cause.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Candidates often confuse the source of 429 errors. In API Gateway, 429 errors indicate throttling at the API Gateway level, not necessarily at the backend. Therefore, increasing backend capacity (Lambda concurrency or DynamoDB throughput) may not resolve the issue if the API Gateway limit is too low.
Detailed technical explanation
How to think about this question
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- API Gateway Throttling
- Cost-Effective Scaling
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
API Gateway Throttling
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.
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.
Review aPI Gateway Throttling, then practise related SAP-C02 questions on the same topic to reinforce the concept.
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Continuous Improvement for Existing Solutions — study guide chapter
Learn the concepts, then practise the questions
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FAQ
Questions learners often ask
What does this SAP-C02 question test?
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — API Gateway Throttling.
What is the correct answer to this question?
The correct answer is: Increase the throttling limits in API Gateway. — The correct answer is C because HTTP 429 errors from API Gateway indicate that the request rate is exceeding the configured throttling limits. Increasing the throttling limits allows more requests to pass through directly, and this is a cost-effective configuration change. Option A (API caching) can reduce backend load but does not address the throttling limit itself. Option B (DynamoDB auto-scaling) addresses DynamoDB capacity, not API Gateway throttling. Option D (Lambda reserved concurrency) addresses Lambda throttling, but the 429 is from API Gateway, not Lambda.
What should I do if I get this SAP-C02 question wrong?
Review aPI Gateway Throttling, then practise related SAP-C02 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
API Gateway Throttling
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Last reviewed: Jun 20, 2026
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.
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