How do you choose between SQS, SNS, EventBridge, and Kinesis?
What they are really testing: A core AWS architecture question. They want you to match the messaging primitive to the pattern (queue vs pub/sub vs event routing vs streaming), not just say "use SQS".
A real interview question
How do you choose between SQS, SNS, EventBridge, and Kinesis?
What most people say
drag me
“They are all for sending messages between services; I would use SQS since it is the standard one.”
It treats them as interchangeable and defaults to SQS. They solve different problems, fan-out, event routing, ordered streaming with replay, and picking wrong means rebuilding later.
The follow-ups they ask next
How do you fan out one event to several independent consumers durably?
SNS-to-SQS: SNS publishes to multiple SQS queues, one per consumer, so each consumer gets its own durable, independently-retryable copy. EventBridge can do similar routing to multiple targets.
When would you pick Kinesis over SQS?
When you need ordering, multiple consumers reading the same records, replay/reprocessing, or sustained high-throughput streaming. SQS deletes a message once consumed and is not built for ordered replay across consumers.
What the interviewer is listening for
- Distinguishes queue / pub-sub / event bus / stream
- Knows SNS-to-SQS fan-out
- Knows Kinesis for ordered replayable streaming
What sinks the answer
- Treats them as interchangeable
- Defaults to SQS for everything
- Cannot articulate fan-out or streaming needs
If you genuinely do not know
Say this instead of freezing. Reasoning out loud from what you do know beats silence every single time, and a good interviewer is listening for exactly that.
“Match the primitive: [SQS = a queue, one consumer pulls work, load leveling]; [SNS = pub/sub fan-out, many subscribers get a copy]; [EventBridge = event bus, content-based routing for event-driven systems]; [Kinesis = ordered, replayable, high-throughput streaming]. Classic combo: [SNS to multiple SQS for durable fan-out].”
Keep going with aws
Foundation
What are the EC2 purchasing options (On-Demand, Reserved, Savings Plans, Spot), and how do you mix them?
Foundation
Walk me through the main S3 storage classes and how you would use lifecycle policies to control cost.
Junior
How does AWS decide whether an IAM request is allowed? Explain the evaluation logic.
Junior
How does an EC2 Auto Scaling Group work, and how would you configure it to scale on load?
Mid
What are VPC endpoints, and when would you use a gateway endpoint versus an interface endpoint?
Mid
How does CloudFront work, and how would you use it to serve a web app efficiently and securely?
Knowing the answer is not the same as recalling it under pressure
Sign in to send the questions you fumble to spaced recall, so they come back right before you would forget them, and learn the concepts behind them with hands-on labs.
Start free