An e-commerce platform has sent online order requests to a standard SQS queue. The visibility timeout for the messages in the queue is set as 30 seconds by default. The message retention period is 7 days. From the backend log system, it has been found that the backend processing of some messages has failed. As a result, these messages were not deleted successfully from the queue. What should you do to isolate the failed messages to troubleshoot the reason why the processing doesn`t succeed?

Answer options:

A.Create a new FIFO queue as the dead letter queue. So the failed messages are isolated and stored in this dead letter queue.
B.Enlarge the visibility timer a little bit and monitor the log system to see if there are still messages that fail to be processed.
C.Modify the visibility timer to 0 to mitigate the impacts when messages are deleted unsuccessfully.
D.Create another SQS standard queue as the dead letter queue. So the problematic messages are isolated.

Correct Answer – D
When messages in an SQS queue can`t be consumed successfully, the messages can be put into a dead-letter queue, ideal for isolating the problematic message.
Option A is incorrect because the queue type for the original queue and dead letter queue should match. Therefore, in this case, the dead letter queue should also be a standard queue.
Option B is incorrect because the visibility timer adjustment does not help to isolate messages that have issues.
Option C is incorrect: Same reason as Option
B. When the visibility timer is modified to 0, visibility timeout is also terminated.
Option D is correct: For example, if the source queue has set maxReceiveCount to 2, and the consumer of the source queue receives a message 2 times without ever deleting it, the message will be put to the dead-letter queue. Then those problematic messages are ready to be analyzed.