88 Topics — 14 Categories
Foundations
Core Principles
How to Approach SD
Structured thinking, top-down vs bottom-up methodology
Scalability
Horizontal vs vertical scaling, unit economics
Reliability
Failure modes, redundancy, graceful degradation
Availability
Nines (99.9→99.999%), SLA/SLO/SLI, failover
Performance
Latency vs throughput, P50/P95/P99 percentiles
CAP Theorem
Why "pick 2 of 3" is misleading, PACELC
ACID vs BASE
Strong vs eventual consistency trade-offs
Estimation
Traffic, storage, bandwidth, QPS calculations
Networking
Internet Basics
TCP/IP stack, what happens when you type a URL
DNS
Hierarchical resolution, GeoDNS, record types
TCP & UDP
Handshakes, congestion control, when to use each
HTTP Evolution
HTTP/1.1 → 2 → 3, QUIC, multiplexing
REST API Design
Resources, methods, status codes, versioning
Webhooks
Push vs poll, HMAC, retry, dead letter queues
Real-time
WebSockets, SSE, long polling, scaling
Proxies
Forward, reverse, Nginx, HAProxy, Envoy
Databases
Relational DBs
ACID, indexing (B+ tree), normalization
Isolation & Locking
4 levels, SKIP LOCKED, MVCC, deadlocks
Schema Design
ER diagrams, soft deletes, migrations
SQL Tuning
EXPLAIN plans, N+1, connection pooling
Scaling DBs
Replication, read replicas, failover, PgBouncer
Sharding
Hash/range/directory, consistent hashing, Vitess
DB Internals
B+ tree, LSM tree, pages, buffer pool, WAL
NoSQL & DB Selection
MongoDB
BSON, flexible schema, aggregation pipeline
Redis Deep Dive
Data structures, persistence, clustering, Lua
Cassandra
Partition keys, gossip protocol, tunable consistency
Neo4j
Cypher, graph traversals, when to use graphs
Caching
Strategies
Cache-aside, write-through, write-behind, refresh-ahead
Eviction Internals
LRU, LFU, Redis TTL sampling, jemalloc
Invalidation
TTL, event-based, cache stampede, thundering herd
CDN
PoPs, push vs pull, edge computing, origin shielding
Caching Levels
Browser → API → Redis → DB, materialized views
Messaging
Message Queues
SQS, RabbitMQ, DLQ, exactly-once delivery
Kafka Deep Dive
Partitions, ISR, consumer groups, compaction
Pub/Sub
Redis Pub/Sub, fan-out, config push patterns
Async Patterns
Task queues, backpressure, flow control
Distributed Systems
Consistency Models
Strong, eventual, causal, linearizability
Consensus
Raft, Paxos, how nodes agree despite failures
Clocks & Ordering
Lamport, vector clocks, TrueTime
Consistent Hashing
Ring, vnodes, data migration, jump hashing
Load Balancing & Resilience
Load Balancers
L4 vs L7, algorithms, health checks, DNS-based
API Gateway
Auth, rate limiting, routing, aggregation
Rate Limiting
Token bucket, sliding window, library vs service
Circuit Breaker
3-state model, bulkhead, exponential backoff
Idempotency
Keys, exactly-once patterns, Stripe's approach
Storage & Data
S3 / Blob Storage
Signed URLs, multipart, erasure coding, 11 nines
Distributed FS
GFS, HDFS, chunk storage, fault tolerance
Tiered Storage
Hot/warm/cold/glacier, cost optimization
Batch Processing
MapReduce, Spark, data locality, lineage
Serialization
Serialization Formats
Protobuf, Avro, Thrift, schema evolution
Compression
gzip, zstd, Snappy, columnar compression
Architecture Patterns
Monolith vs Micro
Trade-offs, decomposition, database per service
Event-Driven
Event sourcing, CQRS, saga, outbox pattern
Service Mesh
Istio, sidecar proxies, Consul, etcd
Communication
sync (REST, gRPC) vs async (events), BFF
Security
Auth
OAuth 2.0, JWT, SSO, RBAC/ABAC, session management
TLS / Encryption
Handshake, certificates, mTLS, KMS
API Security
CORS, CSRF, DDoS, OWASP top 10
Zero Trust
Service-to-service auth, VPC, segmentation
Observability
Logging
Structured logging, ELK, correlation IDs
Metrics
Prometheus, Grafana, RED/USE methods
Tracing
Jaeger, OpenTelemetry, trace/span propagation
Alerting
On-call, runbooks, alert fatigue, postmortems
Infrastructure
Containers & K8s
Docker, pods, services, ingress, scaling
CI/CD
Build, test, deploy, artifacts, GitOps
Deployment
Blue-green, canary, rolling, feature flags
Serverless
Lambda, cold starts, concurrency, event-driven
IaC
Terraform, CloudFormation, immutable infrastructure