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

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.

With Lambda’s SQS event source mapping, messages are delivered with at-least-once semantics. When processing messages in batches (up to 10 per invocation), a common source of unnecessary downstream API calls occurs when only some records in the batch fail. Without special handling, a failure can cause the entire batch to be retried, which means records that were already successfully processed can be delivered again, leading to duplicate calls to the third-party API.

To minimize unnecessary API calls while still preserving at-least-once delivery, the best solution is to enable partial batch response (also described as “report batch item failures”). When enabled, the Lambda function returns a response that explicitly identifies which message(s) failed (by messageId). The event source mapping then retries only the failed messages , while successfully processed messages are deleted from the queue. This reduces duplicates and avoids re-sending already successful records to the third-party API, while still ensuring failed items are retried until they succeed or are moved to a DLQ (if configured).

Option A (FIFO + content-based deduplication) helps prevent duplicate enqueue events within the deduplication window, but it does not stop duplicate deliveries caused by retries, visibility timeouts, or partial failures in a batch. Option B (reserved concurrency = 1) reduces parallelism but does not prevent retries or batch-level duplication; it can also hurt throughput. Option D (DLQ) is important for poison-pill handling but does not reduce duplicate API calls during normal retry behavior; it merely captures messages after the maximum receive count.

Therefore, C is the correct choice: enable batch item failure reporting and implement the function to return partial batch responses so only failed messages are retried, minimizing unnecessary third-party API calls while maintaining at-least-once delivery.

Lambda Destinations on Failure: Allow routing asynchronous function invocations to specified resources (like another Lambda function) upon failure.

Error Handling: The error-handling Lambda receives details about the failure, enabling logging and custom actions.

Direct Integration: This solution leverages native Lambda functionality for a simpler implementation.

Amazon CloudWatch is a service that monitors AWS resources and applications. The developer can use CloudWatch to monitor and troubleshoot all applications from one place. To do so, the developer needs to download the CloudWatch agent to the on-premises server and configure the agent to use IAM user credentials with permissions for CloudWatch. The agent will collect logs and metrics from the on-premises server and send them to CloudWatch.