Area	System design Architecture Message Queues
Phase 1 (junior, mid)	• You need to scale horizontally. How do you route requests to different processes? • How do you discover services? • You need to process files after they are uploaded. How do you do that? • How does perfect log entry look like? • We have the same service deployed to EU and US. It must display same data which is updated 10 times a day at most. Where/how to store data?
Phase 2 (mid, senior)	• How can we prevent DoS? ◦ limit concurrent HTTP connections • How can we prevent backend abuse?  ◦ limit DB connections, max payload size • How to handle 100, 1000 etc concurrent requests? What to keep in mind or how to achieve it? • Whats pub-sub?
Phase 3 (senior+)	• App uses DB + MQ. How to make sure data is not lost? • How can you sync data in different tabs or browsers for the same user without page refresh? ◦ How can you check for user data in the exchange? • What is KTable? • Whats Kafka streams? redis streams?