Mihir Kumar

Your system design knowledge, explaining: - gRPC - CDNs - WebSockets - Rate Limiting - API Gateways - Microservices - Redis Caching - Load Balancers - Message Queues - Database Sharding - Consistent Hashing - Eventual Consistency - Distributed Tracing - Horizontal Scaling - Circuit Breakers - Event Sourcing - Reverse Proxy - CAP Theorem - Service Mesh - Saga Pattern - CQRS - Kafka Interview decision: Sorry, we need someone who can explain why they'd use a database. Knowing the name of a pattern doesn't mean you understand when to use it. I've seen engineers confidently explain microservices architecture, then suggest splitting a 3-table CRUD app into 15 services. They knew the pattern. They didn't know the problem it solves. Understanding fundamentals means asking better questions, for example: 1. Why would I choose PostgreSQL over MongoDB? Not "what are the differences" but what specific requirements in my system make one a better fit. Is it the transaction guarantees? The query flexibility? The team's expertise? 2. When should I NOT use Redis caching? Maybe your data changes too frequently. Maybe cache invalidation becomes more complex than just hitting the database. Maybe you're solving a performance problem that doesn't exist yet. 3. What's the real cost of event sourcing? Sure, you get an audit trail and time travel. But now you're debugging by replaying events, your storage grows unbounded, and your queries need projections. Is that tradeoff worth it for your use case? 4. Do I actually need Kafka? Or would a simple queue work fine for my 1000 requests per day? Are you building for scale you have or scale you imagine? The best engineers I know can explain why they'd choose a boring SQL database over the latest distributed system. They understand the problems these patterns solve AND the problems they create. That's what separates someone who memorized a list from someone who can actually architect systems. ----------------- Check out my Java+Springboot+Microservices+System design ebook curated for interviews here matamgi.com/java-interview-e…