Amazon Web Services Updated DVA-C02 Exam Questions and Answers by koda

Amazon S3 event notifications can invoke AWS Lambda functions at very high rates during traffic spikes. In this scenario, up to 500 objects per minute can result in hundreds of concurrent Lambda invocations. By default, Lambda functions share the account’s unreserved concurrency pool , which can cause throttling if the pool is exhausted by sudden bursts.

AWS Lambda reserved concurrency guarantees a specific number of concurrent executions for a function. By configuring reserved concurrency, the developer ensures that sufficient execution capacity is always available for this specific function, regardless of other Lambda workloads in the account. This prevents throttling during high-volume S3 event bursts.

Increasing the timeout (Option A) does not address concurrency limits. Adding a layer (Option B) does not solve invocation throttling. Decreasing memory (Option D) can actually worsen performance and increase execution time.

AWS documentation explicitly recommends reserved concurrency when workloads experience unpredictable or bursty invocation patterns and must run reliably. Therefore, reserving concurrency is the correct and AWS-recommended solution.

Option B: The target group port in the ALB must match the port specified in the ECS task definition. If there is a mismatch, the ALB health check will fail since it cannot correctly route traffic to the container.

Option E: The ALB listener must have a default action that forwards requests to the correct target group associated with the ECS service. If this configuration is missing, the health check will fail as no traffic is routed to the service.

Option A is irrelevant to resolving health check issues since capacity providers relate to provisioning compute capacity.

Option C (hosted zone) is not directly related to ALB health checks.

Option D (redirecting traffic) is not related to ECS health check configurations.

Requirement Summary:

Simple REST endpoint for weather data

Light backend usage (POC, testing)

Wants caching support to reduce backend calls

Must be cost-effective

Evaluate Options:

B: Lambda + API Gateway + SAM

Serverless = No idle costs

API Gateway can enable caching (response caching at endpoint level)

SAM makes deployment simple and repeatable

Perfect for low-traffic testing

A: EKS + API Gateway

High overhead

Not cost-effective for POC/testing

C: ECS + API Gateway

Similar to A: Container orchestration not needed for light REST endpoint

D: Elastic Beanstalk + ALB + Lambda

Overly complex and does not directly expose Lambda

Beanstalk better suited for full apps, not small REST functions

 AWS SAM: https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/what-is-sam.html

 API Gateway caching: https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-caching.html

 Serverless Best Practices: https://docs.aws.amazon.com/lambda/latest/dg/best-practices.html

Why Option B is Correct:RDS Proxy manages database connections efficiently, reducing overhead on the RDS instance and mitigating " too many connections " errors.

Why Other Options are Incorrect:

Option A: DAX is for DynamoDB, not RDS.

Option C: Migration to PostgreSQL does not address the current issue.

Option D: ElastiCache is useful for caching but does not solve connection pool issues.

AWS Documentation References:

Amazon RDS Proxy