DVA-C02 SQS Redrive Policy Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  The Lambda function's execution role does not have permission to send messages to the DLQ.

  Why it's wrong here

  When an SQS queue's redrive policy is configured to send failed messages to a Dead-Letter Queue (DLQ), it is the SQS service itself that performs the action of moving the message. The Lambda function's execution role is only responsible for permissions related to its own operations, such as reading from the source SQS queue or writing to other AWS services. Therefore, the Lambda function's execution role does not require permissions to send messages to the DLQ; the SQS service handles this internally based on its own permissions and configuration.

• ✓

  The SQS queue's redrive policy is not configured.

  Why this is correct

  When an AWS Lambda function processes messages from an SQS queue, and an invocation fails (e.g., due to an error in the function code or a timeout), SQS will return the message to the queue after its visibility timeout expires. If the message processing continues to fail and the SQS queue does not have a redrive policy configured, the message will eventually be discarded by SQS after its maximum receive count is exceeded, rather than being moved to a Dead-Letter Queue (DLQ). Therefore, a missing redrive policy directly prevents failed messages from being captured in a DLQ associated with the source queue.

• ✗

  The Lambda function's reserved concurrency is set to 0.

  Why it's wrong here

  Setting a Lambda function's reserved concurrency to 0 effectively throttles all invocations, preventing the function from running at all. If this were the case, the function would not be processing any messages from SQS, and thus no messages would be failing or needing to be sent to a DLQ. The problem statement implies the function is running and experiencing occasional failures, making a reserved concurrency of 0 an inconsistent explanation for messages not appearing in a DLQ.

• ✗

  The Lambda function does not have a dead-letter queue configured.

  Why it's wrong here

  For SQS-triggered Lambda functions, the SQS queue itself is responsible for handling failed messages by moving them to a Dead-Letter Queue (DLQ) via its redrive policy. A DLQ configured directly on the Lambda function applies only to asynchronous invocation patterns (e.g., API Gateway, S3 event notifications) where Lambda attempts retries and then sends the failed event to its configured DLQ. Since SQS manages the retry and DLQ logic for its own messages, a Lambda function's internal DLQ configuration is irrelevant in this scenario.

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