Interview prep · 311 cards
System design review cards
Short questions for the ideas system design interviews come back to: a fact to recall, an option to pick, a number to estimate or a gap to fill. Each card has its answer and why it is right.
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Estimation
Back-of-envelope numbers: requests per second, storage, bandwidth and the constants behind them.
21 cards
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Networking
DNS, load balancers, proxies and what happens between the client and the first server.
16 cards
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API design
Endpoints, pagination, idempotency keys and the contracts between services.
17 cards
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Caching
Cache-aside, write policies, eviction, invalidation and hot keys.
21 cards
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Databases
Indexes, storage engines, transactions and choosing a data store.
22 cards
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Replication
Leaders and followers, synchronous and asynchronous copies, and replication lag.
15 cards
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Sharding
Splitting data across machines: partition keys, consistent hashing and hot partitions.
18 cards
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Consistency
CAP, quorums, isolation levels and the guarantees a reader can count on.
19 cards
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Queues
Message queues, pub/sub, delivery guarantees and smoothing load with async work.
18 cards
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Streaming
Logs like Kafka, partitions and ordering, windows and aggregations over events.
18 cards
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Availability
Nines, redundancy, failover and how availability combines across components.
14 cards
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Resilience
Timeouts, retries with backoff, circuit breakers, rate limits and graceful degradation.
16 cards
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Storage
Object, block and file storage, CDNs for big files, and what bytes cost.
14 cards
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Realtime
WebSockets, push, presence and routing messages to connected clients.
15 cards
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Data structures
Bloom filters, HyperLogLog, count-min sketches, geohashes and other tools of scale.
16 cards
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Security
Authentication and authorization, tokens and cookies, TLS between services, secrets, encryption and abuse.
17 cards
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Observability
Metrics, logs and traces, SLOs and error budgets, percentiles and alerting on what users feel.
18 cards
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Coordination
Leader election, consensus, locks and fencing, distributed transactions, sagas and logical clocks.
16 cards