DVA-C02 · Question #245
DVA-C02 Question #245: Real Exam Question with Answer & Explanation
The correct answer is C: The permissions to invoke the Lambda function are missing.. When a Lambda function is registered as an ALB target via CLI, the ALB must be explicitly granted permission to invoke it via a resource-based policy. Without this permission, requests through the ALB will fail silently.
Question
A developer registered an AWS Lambda function as a target for an Application Load Balancer (ALB) using a CLI command. However, the Lambda function is not being invoked when the client sends requests through the ALB. Why is the Lambda function not being invoked?
Options
- AA Lambda function cannot be registered as a target for an ALB.
- BA Lambda function can be registered with an ALB using AWS Management Console only.
- CThe permissions to invoke the Lambda function are missing.
- DCross-zone is not enabled on the ALB.
Explanation
When a Lambda function is registered as an ALB target via CLI, the ALB must be explicitly granted permission to invoke it via a resource-based policy. Without this permission, requests through the ALB will fail silently.
Common mistakes.
- A. Lambda functions can be registered as ALB targets; this is a supported integration since 2018.
- B. Lambda targets can be registered with an ALB using the CLI, SDKs, or CloudFormation, not just the console.
- D. Cross-zone load balancing distributes traffic across Availability Zones and has no bearing on whether a Lambda function can be invoked.
Concept tested. Lambda resource-based policy for ALB invocation
Reference. https://docs.aws.amazon.com/lambda/latest/dg/services-alb.html
Community Discussion
No community discussion yet for this question.