SNS and SQS integration pattern (fan-out) in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

SNS Fan-out Pattern: Message Delivery Count

You have an SNS topic connected to two SQS queues using the fan-out pattern. When a single message is published to the SNS topic, how many messages will each SQS queue receive?

A Each SQS queue receives multiple copies of the message.

B Only one SQS queue receives the message; the other receives none.

C Each SQS queue receives exactly one copy of the message.

D No SQS queue receives the message automatically.

💡 Hint

Think about how SNS distributes messages to multiple subscribers.

In the fan-out pattern, SNS sends a copy of each message to every subscribed SQS queue. So each queue gets exactly one copy.

❓ Architecture

intermediate

Designing for Message Durability in SNS to SQS Fan-out

You want to ensure that messages published to an SNS topic are not lost even if one of the SQS queues is temporarily unavailable. Which configuration best supports this requirement?

A Set SQS queues to non-durable mode to improve performance.

B Use SNS only without SQS queues to simplify the architecture.

C Configure SQS queues without DLQs and rely on SNS to store messages.

D Enable SNS message retries and configure SQS queues with dead-letter queues (DLQs).

💡 Hint

Consider how to handle message failures and retries in distributed systems.

Enabling SNS retries and configuring DLQs on SQS queues ensures messages are retried and not lost if queues are unavailable.

❓ security

advanced

Securing SNS to SQS Fan-out Communication

To restrict which SNS topics can send messages to your SQS queues in a fan-out pattern, what is the best practice?

A Attach an SQS queue policy that allows only specific SNS topic ARNs to send messages.

B Use IAM roles on the SNS topic to restrict sending messages.

C Enable encryption on the SNS topic to block unauthorized messages.

D Configure SNS topic policies to deny all SQS queues.

💡 Hint

Think about how SQS controls who can send messages to it.

SQS queue policies specify which SNS topics are allowed to send messages, controlling access securely.

❓ Configuration

advanced

Configuring SQS Queue to Receive Messages from SNS Topic

Which AWS CLI command correctly subscribes an SQS queue to an SNS topic to implement fan-out?

A aws sns add-subscription --topic arn:aws:sns:region:123456789012:MyTopic --protocol sqs --endpoint arn:aws:sqs:region:123456789012:MyQueue

B aws sns create-subscription --topic-arn arn:aws:sns:region:123456789012:MyTopic --protocol sqs --endpoint arn:aws:sqs:region:123456789012:MyQueue

C aws sns subscribe --topic-arn arn:aws:sns:region:123456789012:MyTopic --protocol sqs --notification-endpoint arn:aws:sqs:region:123456789012:MyQueue

D aws sqs subscribe --queue-url https://sqs.region.amazonaws.com/123456789012/MyQueue --topic-arn arn:aws:sns:region:123456789012:MyTopic

💡 Hint

Check the exact AWS CLI command syntax for SNS subscriptions.

The correct command is aws sns subscribe with the topic ARN, protocol, and endpoint parameters.

✅ Best Practice

expert

Optimizing Throughput in SNS to SQS Fan-out Architecture

You have an SNS topic fan-out to multiple SQS queues. You notice message processing is slow due to high message volume. Which approach best improves throughput without losing messages?

A Enable batching on SQS consumers and increase the number of consumers per queue.

B Reduce the number of SQS queues subscribed to the SNS topic.

C Disable message deduplication on SQS queues to speed up processing.

D Increase the SNS message delivery retry interval to reduce load.

💡 Hint

Think about how to process messages faster in queues.

Batching messages and scaling consumers allows faster processing without message loss.