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DVA-C02 · Question #784

A developer is testing an AWS Lambda function. The developer invokes the Lambda function by using a function URL with an AWS_IAM authentication type. The invocation fails. The developer confirms…

The correct answer is D. Sign the request to the function URL by using the AWS Signature Version 4 (SigV4) signing. When a Lambda function URL is configured with the AWS_IAM authentication type, the caller must authenticate the HTTP request with IAM. That requires signing the request using AWS Signature Version 4 (SigV4) with credentials that have permission to invoke the function URL. The…

Submitted by jaden.t· Mar 5, 2026Development with AWS Services

Question

A developer is testing an AWS Lambda function. The developer invokes the Lambda function by using a function URL with an AWS_IAM authentication type. The invocation fails. The developer confirms that the function URL is correct and that the function's execution role has the lambda:InvokeFunctionUrl permission for the correct resource. However, the invocation continues to fail. The developer must successfully invoke the Lambda function. Which solution will meet this requirement?

Options

  • AAdd a condition to the function's execution role to match StringEquals:
  • BCreate a signed URL by using the function URL and a new public and private key pair. Add the
  • CAdd the lambda:GetFunctionUrlConfig permission to the IAM role that is used to invoke the
  • DSign the request to the function URL by using the AWS Signature Version 4 (SigV4) signing

How the community answered

(30 responses)
  • A
    3% (1)
  • B
    10% (3)
  • C
    17% (5)
  • D
    70% (21)

Explanation

When a Lambda function URL is configured with the AWS_IAM authentication type, the caller must authenticate the HTTP request with IAM. That requires signing the request using AWS Signature Version 4 (SigV4) with credentials that have permission to invoke the function URL. The function’s execution role permissions do not authorize the inbound request; the caller’s signed request does.

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