SDE-2 Interview Preparation Guide
An SDE-2 (mid-level) interview usually has four parts: data structures and algorithms, a system design round, a low-level design or machine-coding round, and a behavioral round about ownership and decisions. The bar rises on design and on how you communicate trade-offs, not only on solving the problem.
A workable plan: two to three weeks of DSA patterns (sliding window, two pointers, trees, graphs, dynamic programming), a week each on HLD and LLD with a few full designs spoken aloud, and the last days on behavioral stories and company-specific preparation.
Questions
- What is High-Level Design (HLD)?
- What is the difference between HLD and LLD?
- What is scalability?
- What is the difference between vertical and horizontal scaling?
- What is availability?
- What is reliability?
- What is fault tolerance?
- What is elasticity?
- What is a stateless service?
- What is a stateful service?
- What is a load balancer?
- What is the difference between Layer 4 and Layer 7 load balancing?
- What is DNS?
- How does DNS resolution work?
- What is a CDN?
- What is a reverse proxy?
- What is an API Gateway?
- What is service discovery?
- What is the difference between client-side and server-side service discovery?
- What is a microservice?
- What is the difference between a monolith and microservices?
- What is horizontal partitioning?
- What is database sharding?
- What is replication?
- What is primary-replica (master-slave) database architecture?
- What is database indexing?
- What is the difference between SQL and NoSQL?
- When would you choose MongoDB?
- When would you choose PostgreSQL?
- What is Redis?
- When should Redis be used?
- What is the cache-aside pattern?
- What is a write-through cache?
- What is a write-back (write-behind) cache?
- What is cache invalidation?
- What is a message queue?
- What is the difference between a queue and a topic?
- What is the difference between Kafka and RabbitMQ?
- What is asynchronous processing?
- What is the difference between synchronous and asynchronous communication?
Related
- DSA: sliding window problems
- Low-level design questions
- Java interview questions
- Amazon SDE-2 interview guide
- Company interview roadmaps
- Solo system design practice, scored out of 10
- Mock interviews
Frequently asked questions
How is an SDE-2 interview different from SDE-1?
More weight on system design and design trade-offs, on owning a feature end to end, and on communication. Coding problems are still there, usually at a medium to hard level.
How long should I prepare for SDE-2?
Most people need six to eight weeks alongside a job. Spend the first weeks on DSA patterns and the rest on design and company-specific rounds.
What system design topics matter most?
Scaling reads and writes, caching, sharding and replication, queues and event-driven design, consistency trade-offs, and designing common systems such as a URL shortener, a chat app, a feed and a rate limiter.