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System Design · Module 10 of 10

Approaching design interviews

Structure your answer and communicate trade-offs.

📖 Key ideas

  1. Clarify requirements and constraints (users, data, latency).
  2. Estimate scale: QPS, storage, bandwidth.
  3. Draw a high-level design: clients, LB, services, DB, cache, queues.
  4. Deep-dive into key components and bottlenecks.
  5. Discuss trade-offs, failures and improvements.
💡 Real-life example: A design interview is a guided city tour: start with the map, then visit key buildings, explaining choices.
Requirements clarificationAgreeing scope first
Capacity estimationRough load and storage numbers
High-level designBig-picture component diagram
Deep diveDetailed look at one component