All Topics

Definition, scope, why it matters — not just for interviews but for everyday engineering decisions

The distinction between micro-level code design (OOP, design patterns) and macro-level system architecture

The 45-minute format, what interviewers evaluate, common mistakes, how FAANG differs from startups

Requirements → Estimation → Service interface → High-level design → API design → Data model → Evaluation → Distinctive features

Recommended learning paths by role and goal: beginner path, interview-prep path, architect path

Powers of 10, latency numbers every engineer should know, throughput and storage estimates, QPS calculations

Vertical vs horizontal scaling, diagonal scaling, measuring scalability with throughput and latency percentiles

SLAs, fault tolerance, redundancy, graceful degradation, chaos engineering

Latency numbers every engineer should know, percentiles, Little's Law, performance vs scalability

How the internet works, DNS, HTTP/HTTPS, HTTP/2, HTTP/3, WebSockets, Server-Sent Events

REST, GraphQL, gRPC, API versioning, rate limiting, API gateways, idempotency

UUID, Snowflake IDs, ULID, auto-increment at scale, time-sortable IDs, ID collision probability

ACID properties, transactions, indexes, query optimization, schema design, joins at scale

Document stores, key-value stores, wide-column stores, graph databases, time-series databases, search engines

CAP theorem, PACELC, eventual consistency, strong consistency, causal consistency

Single-leader, multi-leader, leaderless replication, sync vs async, replication lag

Horizontal vs vertical partitioning, consistent hashing, hot spots, cross-shard transactions

SQL vs NoSQL decision matrix, NewSQL, polyglot persistence

Hash rings, virtual nodes, minimal disruption, weighted distribution, real-world use in DynamoDB, Cassandra, and CDNs

Cache purpose, hit ratio, where to cache — client-side, CDN, application layer, database query cache

LRU, LFU, FIFO, Random, TTL-based, ARC — Adaptive Replacement Cache

Write-through, write-back, write-around, read-through, cache-aside patterns

Cache stampede, avalanche, penetration, invalidation, hot key problem

Redis deep-dive, Memcached, CDN as a cache — when to choose each

Layer 4 vs Layer 7, algorithms, sticky sessions, health checks, GSLB

Forward proxy, reverse proxy, service mesh with Istio and Envoy

Edge nodes, PoPs, cache hierarchy, CDN invalidation, major providers

Client-side vs server-side discovery, DNS-based, Consul, etcd, ZooKeeper

Token bucket, leaky bucket, fixed window, sliding window log, sliding window counter, distributed rate limiting

Temporal decoupling, load levelling, guaranteed delivery, fan-out patterns

Point-to-point, pub/sub, request-reply, dead letter queues, priority & delayed queues

At-most-once, at-least-once, exactly-once, idempotent consumers

Kafka, RabbitMQ, Amazon SQS/SNS, Google Pub/Sub, Redis Streams

Event sourcing, CQRS, Saga pattern, Outbox pattern, Change Data Capture

Partial failures, fallacies of distributed computing, Two Generals problem, Byzantine faults

FLP impossibility, Paxos, Raft, Zab, Viewstamped Replication

Physical clocks, Lamport timestamps, vector clocks, HLC, Google TrueTime

2PC, 3PC, Saga pattern, distributed locking, optimistic vs pessimistic concurrency

Linearizability, sequential consistency, causal consistency, eventual consistency

Block storage, object storage, file storage, in-memory storage

B-trees, LSM trees, SSTable, WAL, MVCC, column-oriented storage

HDFS, Google File System, Amazon S3 architecture, Ceph

JSON, Protocol Buffers, Avro, Parquet/ORC, MessagePack

Bloom filters, count-min sketch, HyperLogLog, cuckoo filters — space-efficient set membership and cardinality

Monolith, modular monolith, SOA, microservices, serverless, event-driven architecture

Single responsibility, bounded context, API-first, database per service, twelve-factor app

Sync vs async communication, service mesh, API gateway, Backend for Frontend

Circuit breaker, retry with backoff, timeout, bulkhead, fallback, health checks

Shared database anti-pattern, Saga, CQRS, event sourcing, API composition

Docker, Kubernetes architecture, scheduling, networking, Helm, service mesh

Multi-region, multi-cloud, IaC, immutable infrastructure, deployment strategies

Logs, metrics, traces, SLI/SLO/SLA, error budgets, on-call and incident response

AuthN/AuthZ, OAuth 2.0, JWT, mTLS, secrets management, DDoS protection, zero trust

ZooKeeper, etcd, leader election algorithms, distributed locks and fencing tokens

Amazon Dynamo, Google Bigtable, Google Spanner, Facebook TAO, Cassandra deep dive

Kafka Streams, Apache Flink, Spark Streaming, windowing, backpressure handling

Data pipelines, data lakes, warehouses, Apache Spark, MapReduce, columnar databases

Multi-region replication, data sovereignty, CRDTs, operational transformation

Online vs offline ML, feature stores, training pipelines, model serving, A/B testing, monitoring

Collaborative & content-based filtering, two-tower architecture, cold start, ranking

Inverted index, Elasticsearch, relevance scoring, vector search, hybrid search

LLM inference infrastructure, RAG, API design, prompt caching, fine-tuning, safety

Agent architecture, tool calling, memory systems, multi-agent orchestration, human-in-the-loop

WhatsApp, notification system, real-time chat, email service, video conferencing

Twitter/X, Instagram, YouTube, news feed, Reddit, TikTok

Amazon, flash sale system, payment system, Airbnb, Uber

URL shortener, rate limiter, web crawler, KV store, search engine, Google Docs, Kafka, S3

Live leaderboard, stock ticker, Google Maps, nearby friends, food delivery

CI/CD pipeline, deployment system, API gateway, metrics system, logging system, feature flags

RESHADED framework, requirements gathering, estimation techniques, trade-off communication, diagramming

Google, Meta, Amazon, Netflix, Uber — company-specific expectations and interview styles

Tier 1-4 questions from beginner to AI-era, plus whiteboard rubric for self-evaluation