- A
Configure the Lambda authorizer only on the POST method in the API Gateway.
Authorizers can be applied per method.
- B
Create a Lambda function as an authorizer that validates a JWT token from the Authorization header.
Lambda authorizer can validate tokens and return an IAM policy.
- C
In the Lambda authorizer, return an IAM policy that allows execute-api:Invoke on the POST method.
The authorizer returns a policy document that grants or denies access.
- D
Use an Amazon Cognito User Pools authorizer for the entire API.
Why wrong: This would apply to all methods, not just POST.
- E
Add a resource policy that denies public access to the POST method.
Why wrong: Resource policies affect the whole API, not specific methods.
Question 1,579 of 1,616
Securing Specific API Gateway Methods with Lambda Authorizer for OAuth 2.0
This DVA-C02 practice question tests your understanding of development with aws services. 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. 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 uses Amazon API Gateway to expose a REST API backed by AWS Lambda. The API has a resource /items with GET and POST methods. The GET method returns items from a DynamoDB table. The POST method adds an item to the table. Currently, all methods are open to the public. Security requirements mandate that only authenticated users can access the POST method, while the GET method remains public. Which THREE steps should the developer take to meet these requirements?
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
✓
Configure the Lambda authorizer only on the POST method in the API Gateway.
Option A is correct because you can configure a Lambda authorizer at the method level in API Gateway, which allows you to selectively secure only the POST method while leaving the GET method public. This meets the requirement of restricting access to authenticated users for POST only, without affecting the public GET endpoint.
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.
- ✓
Configure the Lambda authorizer only on the POST method in the API Gateway.
Why this is correct
Authorizers can be applied per method.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Create a Lambda function as an authorizer that validates a JWT token from the Authorization header.
Why this is correct
Lambda authorizer can validate tokens and return an IAM policy.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
In the Lambda authorizer, return an IAM policy that allows execute-api:Invoke on the POST method.
Why this is correct
The authorizer returns a policy document that grants or denies access.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use an Amazon Cognito User Pools authorizer for the entire API.
Why it's wrong here
This would apply to all methods, not just POST.
- ✗
Add a resource policy that denies public access to the POST method.
Why it's wrong here
Resource policies affect the whole API, not specific methods.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume a resource policy can be used to selectively restrict methods, but resource policies apply at the API or stage level, not at the individual method level, making them unsuitable for this granular requirement.
Detailed technical explanation
How to think about this question
A Lambda authorizer (formerly custom authorizer) returns an IAM policy document that grants or denies execute-api:Invoke access to specific ARNs, such as arn:aws:execute-api:{region}:{account}:{api-id}/{stage}/{method}/{resource}. By scoping the policy to the POST method's ARN, the authorizer ensures only authenticated requests with a valid JWT token can invoke that method, while unauthenticated requests to GET are unaffected because no authorizer is attached to it.
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
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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: Configure the Lambda authorizer only on the POST method in the API Gateway. — Option A is correct because you can configure a Lambda authorizer at the method level in API Gateway, which allows you to selectively secure only the POST method while leaving the GET method public. This meets the requirement of restricting access to authenticated users for POST only, without affecting the public GET endpoint.
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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Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
3 more ways this is tested on DVA-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A developer is building an API using Amazon API Gateway and AWS Lambda. The API must authenticate users using a third-party OAuth 2.0 provider. Which THREE components are required to implement this authentication?
hard- ✓ A.The OAuth 2.0 access token in the Authorization header
- B.Amazon CloudFront distribution for API caching
- C.An API Gateway resource policy that invokes the Lambda authorizer
- ✓ D.An AWS Lambda authorizer function
- E.An Amazon Cognito user pool as the OAuth provider
Why A: Option A is correct because the OAuth 2.0 access token must be sent in the Authorization header for the Lambda authorizer to validate. Option D is correct because the Lambda authorizer function is responsible for decoding and verifying the token against the third-party OAuth provider. Option C is incorrect because a resource policy controls access to the API but does not invoke the authorizer; the authorizer is configured via API Gateway authorizer settings, not a resource policy. Therefore, only options A and D are the required components.
Variation 2. A company is using Amazon API Gateway to expose a REST API. The API must authenticate requests using an external OAuth 2.0 provider. Which API Gateway feature should be used?
medium- A.IAM authorization
- B.Resource policy
- ✓ C.Lambda authorizer
- D.Amazon Cognito User Pools
Why C: Option C is correct because a Lambda authorizer (formerly known as a custom authorizer) allows you to implement custom authentication logic using an external OAuth 2.0 provider. The Lambda function receives the OAuth 2.0 bearer token from the request, validates it against the external provider's token introspection endpoint or by verifying the JWT signature, and returns an IAM policy that grants or denies access to the API Gateway method.
Variation 3. A developer is using Amazon API Gateway with a Lambda authorizer to control access to an API. The authorizer function needs to decode a JWT token from the request header and return an IAM policy. Which type of Lambda authorizer should be used?
medium- ✓ A.TOKEN authorizer with the token passed in the Authorization header.
- B.REQUEST authorizer with the token in a custom header.
- C.Use Amazon Cognito User Pools as the authorizer.
- D.Use a resource policy to allow or deny access based on the JWT token.
Why A: A TOKEN authorizer is designed to receive a JWT or OAuth token in the Authorization header and pass it directly to the Lambda function for validation. The Lambda function then decodes the token and returns an IAM policy document to allow or deny the API request. This is the correct choice because the question explicitly states the token is in the request header and needs to be decoded, which matches the TOKEN authorizer's behavior of forwarding the raw token value.
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Last reviewed: Jul 4, 2026
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