- A
Use an API Gateway resource policy to allow only authenticated users.
Why wrong: Resource policy controls access based on IP or VPC, not OAuth tokens.
- B
Use a Lambda authorizer in API Gateway to validate the OAuth token.
Lambda authorizer can call the OAuth provider.
- C
Configure Amazon Cognito User Pools as an OAuth 2.0 provider and use its integration with API Gateway.
Cognito can act as an OAuth provider and be used as an authorizer.
- D
Use IAM authorization with a custom token service.
Why wrong: IAM authorization uses AWS SigV4, not OAuth tokens.
- E
Implement token validation in a custom Lambda function that is invoked before processing the request.
The function can validate tokens from the OAuth provider.
Question 1,438 of 1,616
API Gateway OAuth 2.0: Lambda Authorizer & Cognito
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.
A developer is building a serverless application using AWS Lambda and Amazon API Gateway. The application must authenticate users using a third-party OAuth 2.0 provider. Which THREE options can the developer use to integrate with the OAuth provider?
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 a Lambda authorizer in API Gateway to validate the OAuth token.
Option B is correct because a Lambda authorizer (formerly known as a custom authorizer) in API Gateway can validate OAuth 2.0 tokens by calling a Lambda function that verifies the token's signature, expiry, and claims against the third-party provider's public keys or introspection endpoint. This allows fine-grained access control without modifying the backend Lambda function.
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 an API Gateway resource policy to allow only authenticated users.
Why it's wrong here
Resource policy controls access based on IP or VPC, not OAuth tokens.
- ✓
Use a Lambda authorizer in API Gateway to validate the OAuth token.
Why this is correct
Lambda authorizer can call the OAuth provider.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Configure Amazon Cognito User Pools as an OAuth 2.0 provider and use its integration with API Gateway.
Why this is correct
Cognito can act as an OAuth provider and be used as an authorizer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use IAM authorization with a custom token service.
Why it's wrong here
IAM authorization uses AWS SigV4, not OAuth tokens.
- ✓
Implement token validation in a custom Lambda function that is invoked before processing the request.
Why this is correct
The function can validate tokens from the OAuth provider.
Related concept
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 IAM authorization (Option D) with OAuth 2.0, thinking IAM can directly validate third-party tokens, but IAM only works with AWS credentials and Signature V4, not bearer tokens.
Detailed technical explanation
How to think about this question
Lambda authorizers can return an IAM policy document that API Gateway caches for up to 1 hour (configurable via TTL), reducing latency for subsequent requests. Under the hood, the authorizer receives the OAuth token in the Authorization header and must verify it using the provider's JWKS endpoint (RFC 7517) or token introspection (RFC 7662). A common real-world scenario is using Auth0 or Okta as the third-party provider, where the Lambda authorizer fetches the JWKS set to verify the token's signature locally.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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 a Lambda authorizer in API Gateway to validate the OAuth token. — Option B is correct because a Lambda authorizer (formerly known as a custom authorizer) in API Gateway can validate OAuth 2.0 tokens by calling a Lambda function that verifies the token's signature, expiry, and claims against the third-party provider's public keys or introspection endpoint. This allows fine-grained access control without modifying the backend Lambda function.
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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