What is a DLQ?

• A. It stores delivered messages for auditing.
• B. It is a queue that only receives undelivered messages.
• C. It handles message routing to multiple queues.
• D. It is a dead-letter queue for errors irrelevant to business logic.

Answer: (B)

A dead-letter queue is a special destination for messages that cannot be delivered to their intended consumer or cannot be processed successfully. When a message keeps failing to be delivered or processed after retries, it’s moved to this separate queue so the main processing flow isn’t blocked and experts can inspect, reprocess, or analyze the problem later. The option describing a DLQ as a queue that only receives undelivered messages captures this behavior, since the purpose is to isolate messages that couldn’t be delivered or processed. The other options describe auditing delivered messages, routing to multiple queues, or labeling errors as irrelevant to business logic, which aren’t accurate descriptions of a DLQ’s role.