System Design & Architecture Interview Questions practice questions
10 questions in 1 test. Open one to answer it on its own, or take a whole test.
Test 1
Take Test 1 ›- A concert-ticketing service stores seat inventory in a database replicated across three sites. The business rule is absolute: a seat must never be sold to two people, and the… · CAP & Consistency Models
- A social app sends all writes to a leader database and load-balances reads across several asynchronously replicated followers. Users complain that after they edit their bio and… · CAP & Consistency Models
- An e-commerce home page shows a "today's deals" block. It is computed by an aggregate database query that takes about 2 seconds and is cached with the cache-aside pattern under a… · Caching
- A web application exposes a single public hostname over HTTPS. Requests whose URL path starts with /api/ must go to a fleet of API servers, and requests under /static/ must go to… · Load Balancing
- A multi-tenant analytics service stores events in a database sharded by hash(tenant_id) across 16 shards. One very large tenant now produces about 40% of all writes. Its shard is… · Sharding & Partitioning
- A ledger service runs a leader database with one follower in another datacenter. Replication is asynchronous. The leader's host crashed, and automated failover promoted the… · Replication
- A public API limits each API key to 100 requests per minute using a fixed-window counter that resets at the start of every clock minute. An abusive client sends 100 requests at… · Rate Limiting & Back-pressure
- A storage service had a 20-second outage. About 5,000 client processes call it, and each retries failed requests with exponential backoff of exactly 1 s, 2 s, 4 s and 8 s. After… · Retries & Idempotency
- A checkout service puts a "charge order" message on a queue that guarantees at-least-once delivery. A worker takes each message, calls the payment processor, and then… · Retries & Idempotency
- A web application runs on one server that is already the largest instance size the provider offers. At peak it runs at 90% CPU, and traffic is expected to triple within a year… · Scalability