Domain 5: Define Operationally Excellent Architectures

1. B. AWS does guarantee that all SQS messages will be delivered at least once, but the message may be delivered more than once (making option A incorrect). This is not related to the number of requests to the queue or the applications using the queue; therefore, both C and D are incorrect. This leaves B, the correct answer.
2. B, C. This is a common question AWS often asks to ensure that you understand that managed services like RDS and DynamoDB are indeed completely managed: You cannot access the underlying operating system of the service. This leaves EC2 and EMR as the remaining, and correct, answers. While EMR does provide you with a lot of functionality “out of the box,” it still allows root level access, as do EC2 instances.
3. C. SQS queues have a visibility timeout that controls how long a message in the queue is marked as “invisible” while being processed. This accounts for the message “disappearing...