Certified Solutions Architect Decoupling with SQS and SNS Flashcards
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Read the first 7 Certified Solutions Architect Decoupling with SQS and SNS flashcards as text
A company publishes events to an SNS FIFO topic and subscribes an SQS FIFO queue. Which statement about this configuration is true?
Answer: SNS FIFO topics can only deliver to SQS FIFO queues, not Standard queues
SNS FIFO topics support only SQS FIFO queue subscriptions to maintain end-to-end ordering and deduplication guarantees.
A processing application reads from SQS and takes up to 10 minutes to handle each message. The default visibility timeout is 30 seconds. What is the correct fix to prevent duplicate processing?
Answer: Use ChangeMessageVisibility to extend the timeout dynamically during processing
Calling ChangeMessageVisibility during processing extends the timeout before it expires, preventing the message from becoming visible while still being processed.
Which SQS metric should be monitored to trigger Auto Scaling of consumer EC2 instances based on queue depth?
Answer: ApproximateNumberOfMessagesVisible
ApproximateNumberOfMessagesVisible represents the number of messages available for retrieval and is the standard metric used to scale consumers via CloudWatch alarms.
A company wants to implement a dead-letter queue for an SNS subscription to an HTTP endpoint. Which statement is accurate?
Answer: SNS supports SQS-based DLQs for failed deliveries to HTTP, Lambda, and SQS subscribers
SNS supports setting an SQS queue as a dead-letter queue (redrive policy) on subscriptions, capturing messages that exhaust all delivery retries.
What differentiates an SQS FIFO queue's throughput in high-throughput mode compared to standard FIFO mode?
Answer: High-throughput mode increases the quota to 70,000 messages/second per API action without sacrificing FIFO ordering within a message group
FIFO high-throughput mode raises the per-queue quota to 70,000 transactions per second while preserving per-message-group ordering and exactly-once semantics.
An architect needs to decouple microservices so that a failure in the email service does not affect the order service. The order service must continue accepting orders regardless. Which pattern achieves this?
Answer: Order service publishes to an SNS topic; email service subscribes via SQS queue
Publishing to SNS with an SQS buffer for the email service fully decouples the two services; the email service's failures do not block order processing.
A solutions architect needs to guarantee that only authorized AWS accounts can subscribe to a sensitive SNS topic. Which mechanism enforces this?
Answer: Attach an SNS topic policy restricting sns:Subscribe to specific AWS account ARNs
An SNS topic resource policy with a Condition on aws:PrincipalAccount restricts which accounts can call sns:Subscribe, preventing unauthorized subscriptions.