DVA-C02 Development with AWS Services Practice Question
This DVA-C02 practice question tests your understanding of development with aws services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
An independent software vendor (ISV) is building a serverless application that processes incoming HTTP requests. The incoming requests must be validated against an OpenAPI schema before being passed to the Lambda function. Which AWS service should the ISV use to perform this validation?
Correct. API Gateway can validate requests against an OpenAPI schema before forwarding them to the Lambda function, reducing unnecessary invocations and improving security.
B
AWS WAF
Why wrong: Incorrect. AWS WAF is a web application firewall that protects against common web exploits; it does not perform schema-based validation of API payloads.
C
Amazon Cognito
Why wrong: Incorrect. Amazon Cognito provides authentication, authorization, and user management, not request payload validation.
D
AWS AppSync
Why wrong: Incorrect. AWS AppSync is a managed GraphQL service; while it can validate GraphQL requests, it is not designed for RESTful API schema validation in the same way as API Gateway.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Amazon API Gateway (with request validation)
Amazon API Gateway's request validation feature can validate incoming HTTP requests against an OpenAPI (Swagger) schema before the request reaches the Lambda function. This offloads validation from the Lambda code, reducing cost and latency by rejecting invalid requests early. The ISV can define the schema in the API Gateway REST API or HTTP API, and API Gateway will automatically check headers, query strings, and request bodies against the schema.
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.
✓
Amazon API Gateway (with request validation)
Why this is correct
Correct. API Gateway can validate requests against an OpenAPI schema before forwarding them to the Lambda function, reducing unnecessary invocations and improving security.
Related concept
Read the scenario before looking for a memorised answer.
✗
AWS WAF
Why it's wrong here
Incorrect. AWS WAF is a web application firewall that protects against common web exploits; it does not perform schema-based validation of API payloads.
✗
Amazon Cognito
Why it's wrong here
Incorrect. Amazon Cognito provides authentication, authorization, and user management, not request payload validation.
✗
AWS AppSync
Why it's wrong here
Incorrect. AWS AppSync is a managed GraphQL service; while it can validate GraphQL requests, it is not designed for RESTful API schema validation in the same way as API Gateway.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing AWS WAF's ability to inspect HTTP requests (e.g., body size, headers) with API Gateway's schema-based validation, leading candidates to choose WAF for payload validation instead of API Gateway's built-in request validation.
Detailed technical explanation
How to think about this question
API Gateway's request validation works by comparing the incoming request against a JSON Schema derived from the OpenAPI definition. When validation fails, API Gateway returns a 400 Bad Request with a detailed error message (e.g., 'request body does not match schema'), without invoking the Lambda function. This is especially useful in high-traffic serverless applications where early rejection of malformed requests can significantly reduce Lambda invocations and associated costs.
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.
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: Amazon API Gateway (with request validation) — Amazon API Gateway's request validation feature can validate incoming HTTP requests against an OpenAPI (Swagger) schema before the request reaches the Lambda function. This offloads validation from the Lambda code, reducing cost and latency by rejecting invalid requests early. The ISV can define the schema in the API Gateway REST API or HTTP API, and API Gateway will automatically check headers, query strings, and request bodies against the schema.
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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