- A
Use API Gateway request validation with a model schema.
API Gateway can validate requests before invoking Lambda, saving costs.
- B
Validate the request in the Lambda function and return errors if validation fails.
Why wrong: This still invokes Lambda, costing money and time.
- C
Use Amazon CloudFront to validate the request at the edge.
Why wrong: CloudFront is not designed for API request validation.
- D
Use API Gateway request parameters to enforce required headers.
Why wrong: This only validates parameters, not the payload body.
Question 1,497 of 1,616
API Gateway Request Validation
This DVA-C02 practice question tests your understanding of development with aws services. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 using Amazon API Gateway to expose a REST API. The API needs to validate request parameters and payload before invoking the backend Lambda function. What is the MOST efficient way to perform this validation?
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
✓
Use API Gateway request validation with a model schema.
API Gateway's built-in request validation allows you to define a JSON Schema model that automatically validates request parameters, headers, and payload before the request reaches the backend Lambda function. This offloads validation from the Lambda function, reducing compute time and cost, and provides immediate 400 error responses without invoking the backend. It is the most efficient approach because it minimizes latency and Lambda invocations for invalid requests.
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.
- ✓
Use API Gateway request validation with a model schema.
Why this is correct
API Gateway can validate requests before invoking Lambda, saving costs.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Validate the request in the Lambda function and return errors if validation fails.
Why it's wrong here
This still invokes Lambda, costing money and time.
- ✗
Use Amazon CloudFront to validate the request at the edge.
Why it's wrong here
CloudFront is not designed for API request validation.
- ✗
Use API Gateway request parameters to enforce required headers.
Why it's wrong here
This only validates parameters, not the payload body.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume validation must happen in the Lambda function (Option B) because they think backend logic is required, but API Gateway's built-in request validation is more efficient and is the recommended approach for schema-based validation before invocation.
Detailed technical explanation
How to think about this question
API Gateway request validation uses JSON Schema (draft-04) models defined in the API Gateway REST API, which are applied at the integration request stage. When validation fails, API Gateway returns a 400 Bad Request response with a detailed error message, such as 'Missing required request parameters' or 'Model validation failed', without ever invoking the backend. This is particularly useful for high-traffic APIs where early rejection of malformed requests can significantly reduce backend load and cost.
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.
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.
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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: Use API Gateway request validation with a model schema. — API Gateway's built-in request validation allows you to define a JSON Schema model that automatically validates request parameters, headers, and payload before the request reaches the backend Lambda function. This offloads validation from the Lambda function, reducing compute time and cost, and provides immediate 400 error responses without invoking the backend. It is the most efficient approach because it minimizes latency and Lambda invocations for invalid requests.
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: Jul 4, 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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