System Design & Distributed Systems

How to approach SD interviews, framework, trade-offs

TCP/UDP, HTTP, DNS, CDN, WebSockets

REST, gRPC, GraphQL, webhooks, long polling, SSE

SQL vs NoSQL, ACID, BASE, data modeling

L4/L7 LB, algorithms, health checks, HAProxy/Nginx

Cache strategies, eviction, Redis, Memcached, CDN caching

Indexing, sharding, replication, partitioning, query optimization

Kafka, RabbitMQ, SQS, pub/sub, event-driven architecture

Hash rings, virtual nodes, partition strategies

CAP, PACELC, strong/eventual/causal consistency

Paxos, Raft, ZAB, leader election, split brain

Single-leader, multi-leader, leaderless, quorum

2PC, 3PC, Saga pattern, TCC, idempotency

Lamport clocks, vector clocks, HLC, causality

Vertical vs horizontal, stateless services, auto-scaling

Service decomposition, API gateway, service mesh, sidecar

Token bucket, leaky bucket, sliding window, distributed RL

UUID, Snowflake, ULID, Twitter Snowflake, DB sequences

Bloom filter, Count-Min Sketch, HyperLogLog

S3, HDFS, GFS, blob storage

Inverted index, Elasticsearch, full-text search, ranking

InfluxDB, TimescaleDB, ClickHouse, OLAP vs OLTP

Batch vs stream, MapReduce, Spark, Flink, data lake

SLA/SLO/SLI, failure modes, circuit breaker, bulkhead, retry

Prometheus, Grafana, ELK, distributed tracing, alerting

AuthN/AuthZ, OAuth2, JWT, mTLS, zero trust

TinyURL, hash generation, analytics

Distributed rate limiting, Redis-based

Dynamo-style, consistent hashing, conflict resolution

Push, email, SMS, fanout, priority, templates

WhatsApp/Messenger, presence, delivery receipts, E2E

Facebook/Twitter feed, fanout-on-write vs read, ranking

Video upload, transcoding, streaming, CDN, recommendations

Web crawler, indexing, PageRank, serving

Geo-spatial, matching, ETA, surge pricing

Tweets, timeline, trends, search

File sync, chunking, dedup, conflict resolution

BFS crawling, URL frontier, politeness, dedup

Trie, prefix search, ranking, real-time suggestions

Memcached/Redis cluster, consistent hashing, replication

Concurrency, seat locking, payment, consistency

Stripe-like, idempotency, reconciliation, ledger

CRDTs, operational transforms, collaborative editing

SWIM, gossip dissemination, failure detection

Multi-region, active-active, latency optimization

Feature store, model serving, A/B testing infra

The 4-step framework, time management, communication