Updated Sep 19, 2026

Glossary

Auto-generated index of key terms and which lesson covers them.

Term Lesson
0-RTT connection setup 03. Networking Fundamentals
3-way handshake 03. Networking Fundamentals
429 Too Many Requests 19. Rate Limiting
ACID 09. Databases: SQL vs NoSQL
Active-active 06. Load Balancers
Active-passive 06. Load Balancers
Amazon SQS 15. Message Queues
anycast 08. Content Delivery Networks
AP 13. Consistency and CAP Theorem
API gateway 17. API Design and Gateways
at-least-once 01. The System Design Process, 15. Message Queues
At-most-once 15. Message Queues
atomic check-and-set 16. Idempotency and Exactly-Once Delivery
Authoritative nameserver 03. Networking Fundamentals
availability zones 21. Designing for Failure
AWS Fault Injection Simulator 21. Designing for Failure
AWS X-Ray 20. Monitoring and Observability
B-trees 10. Indexing and Denormalization
BGP 08. Content Delivery Networks
Block Storage 12. Object Storage and Uploads
bottleneck 04. Scaling and Bottlenecks
Browser cache 07. Caching
buffer pool 07. Caching
bulkheads 21. Designing for Failure
Cache-aside 07. Caching
Cache-Control 08. Content Delivery Networks
caching 01. The System Design Process
canary deploys 03. Networking Fundamentals
CAP theorem 13. Consistency and CAP Theorem
Cassandra 09. Databases: SQL vs NoSQL
Causal consistency 13. Consistency and CAP Theorem
CDN 01. The System Design Process, 08. Content Delivery Networks
Chaos Monkey 21. Designing for Failure
circuit breaker 21. Designing for Failure
circuit breakers 04. Scaling and Bottlenecks
Cloudflare 08. Content Delivery Networks
Cloudflare Workers 08. Content Delivery Networks
CloudWatch 20. Monitoring and Observability
CockroachDB 14. PACELC and Consensus
composite index 10. Indexing and Denormalization
Congestion control 03. Networking Fundamentals
Connection migration 03. Networking Fundamentals
Connection registry 18. Real-Time Communication
Consensus algorithms 14. PACELC and Consensus
Consistent hashing 06. Load Balancers, 11. Database Replication and Sharding
Constraints 01. The System Design Process
Consul 05. Proxies and Service Communication, 14. PACELC and Consensus
consumer groups 15. Message Queues
consumers 15. Message Queues
CP 13. Consistency and CAP Theorem
Cursor-based pagination 17. API Design and Gateways
Datadog 20. Monitoring and Observability
DAU 02. Back-of-Envelope Estimation
DDoS 08. Content Delivery Networks
dead letter queue 15. Message Queues
deduplication 01. The System Design Process
Denormalization 10. Indexing and Denormalization
Directory-based sharding 11. Database Replication and Sharding
distributed cluster 02. Back-of-Envelope Estimation
distributed systems 05. Proxies and Service Communication
DNS 03. Networking Fundamentals, 08. Content Delivery Networks
Document stores 09. Databases: SQL vs NoSQL
dotted version vectors 13. Consistency and CAP Theorem
DynamoDB 09. Databases: SQL vs NoSQL
EBS 12. Object Storage and Uploads
edge locations 08. Content Delivery Networks
Edge-side includes 08. Content Delivery Networks
EFS 12. Object Storage and Uploads
Elasticsearch 09. Databases: SQL vs NoSQL
ELK Stack 20. Monitoring and Observability
Envoy 05. Proxies and Service Communication
Error budgets 20. Monitoring and Observability
ETag 07. Caching
etcd 05. Proxies and Service Communication, 14. PACELC and Consensus
Event streams 05. Proxies and Service Communication
Event-driven invalidation 07. Caching
eventual consistency 01. The System Design Process, 13. Consistency and CAP Theorem
Exactly-once 15. Message Queues
Exponential backoff 21. Designing for Failure
failover 11. Database Replication and Sharding
fan-out 10. Indexing and Denormalization
FCM 01. The System Design Process
FIFO 07. Caching
File Storage 12. Object Storage and Uploads
Fixed Window 19. Rate Limiting
Flow control 03. Networking Fundamentals
Followers 11. Database Replication and Sharding
forward proxy 05. Proxies and Service Communication
full table scan 10. Indexing and Denormalization
full-duplex 18. Real-Time Communication
Functional requirements 01. The System Design Process
GCS 12. Object Storage and Uploads
GeoDNS 03. Networking Fundamentals
Global Secondary Index 09. Databases: SQL vs NoSQL
golden signals 20. Monitoring and Observability
Graph databases 09. Databases: SQL vs NoSQL
GraphQL 05. Proxies and Service Communication, 17. API Design and Gateways
Gremlin 21. Designing for Failure
gRPC 05. Proxies and Service Communication, 17. API Design and Gateways
HAProxy 05. Proxies and Service Communication
Hash indexes 10. Indexing and Denormalization
Hash-based sharding 11. Database Replication and Sharding
HDD 02. Back-of-Envelope Estimation
Head-of-line (HOL) blocking 03. Networking Fundamentals
Header compression 03. Networking Fundamentals
health check 06. Load Balancers
Horizontal scaling 04. Scaling and Bottlenecks
HTTP/2 17. API Design and Gateways
HTTP/REST 05. Proxies and Service Communication
hybrid logical clocks 13. Consistency and CAP Theorem
ICE 18. Real-Time Communication
idempotency key 16. Idempotency and Exactly-Once Delivery
idempotent 01. The System Design Process, 15. Message Queues
idempotent operation 16. Idempotency and Exactly-Once Delivery
IP Hash 06. Load Balancers
Istio 05. Proxies and Service Communication
Jaeger 20. Monitoring and Observability
Jitter 21. Designing for Failure
joins 09. Databases: SQL vs NoSQL
Kafka 01. The System Design Process, 15. Message Queues
Key-value stores 09. Databases: SQL vs NoSQL
Kinesis 05. Proxies and Service Communication
Kubernetes 01. The System Design Process
Lambda@Edge 08. Content Delivery Networks
Lamport clocks 13. Consistency and CAP Theorem
Latency 04. Scaling and Bottlenecks
Layer 4 06. Load Balancers
Layer 7 06. Load Balancers
leader 11. Database Replication and Sharding
Leaky Bucket 19. Rate Limiting
Least Connections 06. Load Balancers
LFU 07. Caching
Lifecycle policies 12. Object Storage and Uploads
Linkerd 05. Proxies and Service Communication
Litmus 21. Designing for Failure
Load Balancer 01. The System Design Process, 06. Load Balancers
Logs 20. Monitoring and Observability
Loki 20. Monitoring and Observability
long polling 18. Real-Time Communication
LRU 07. Caching
materialized view 10. Indexing and Denormalization
Memcached 07. Caching, 09. Databases: SQL vs NoSQL
Message queues 05. Proxies and Service Communication
Metrics 20. Monitoring and Observability
Microservices 01. The System Design Process
MongoDB 09. Databases: SQL vs NoSQL
Monitoring 20. Monitoring and Observability
mTLS 05. Proxies and Service Communication
Multi-leader replication 11. Database Replication and Sharding
Multipart Upload 12. Object Storage and Uploads
Multiplexing 03. Networking Fundamentals
MySQL 09. Databases: SQL vs NoSQL
Neo4j 09. Databases: SQL vs NoSQL
Nginx 05. Proxies and Service Communication, 08. Content Delivery Networks
Non-functional requirements 01. The System Design Process
Normalization 10. Indexing and Denormalization
normalize 09. Databases: SQL vs NoSQL
NoSQL 09. Databases: SQL vs NoSQL
object storage 02. Back-of-Envelope Estimation, 12. Object Storage and Uploads
Observability 20. Monitoring and Observability
offset-based pagination 17. API Design and Gateways
OpenTelemetry 20. Monitoring and Observability
Origin Access Control 12. Object Storage and Uploads
over-fetching 17. API Design and Gateways
p99 latency 04. Scaling and Bottlenecks
PA/EL 14. PACELC and Consensus
PACELC 14. PACELC and Consensus
Pareto principle 02. Back-of-Envelope Estimation
partition key 09. Databases: SQL vs NoSQL
Paxos 14. PACELC and Consensus
PC/EC 14. PACELC and Consensus
peer-to-peer 18. Real-Time Communication
Persistent connections 03. Networking Fundamentals
polling 18. Real-Time Communication
POSIX 12. Object Storage and Uploads
POST policies 12. Object Storage and Uploads
PostgreSQL 01. The System Design Process, 09. Databases: SQL vs NoSQL
pre-signed URL 12. Object Storage and Uploads
Probabilistic early expiration 07. Caching
producers 15. Message Queues
Prometheus 20. Monitoring and Observability
Propagation delay 03. Networking Fundamentals
Protocol Buffers 05. Proxies and Service Communication, 17. API Design and Gateways
Proxies 05. Proxies and Service Communication
Pub/Sub 15. Message Queues
publish-subscribe 05. Proxies and Service Communication
QPS 02. Back-of-Envelope Estimation
queue 01. The System Design Process
QUIC 03. Networking Fundamentals
RabbitMQ 05. Proxies and Service Communication, 15. Message Queues
Raft 14. PACELC and Consensus
Range-based sharding 11. Database Replication and Sharding
read replicas 04. Scaling and Bottlenecks
Read-through 07. Caching
read-to-write ratio 02. Back-of-Envelope Estimation
Read-your-writes 13. Consistency and CAP Theorem
Recursive resolver 03. Networking Fundamentals
Redis 01. The System Design Process, 07. Caching, 09. Databases: SQL vs NoSQL, 19. Rate Limiting
Redis SET NX 16. Idempotency and Exactly-Once Delivery
Redis Streams 15. Message Queues
Relational databases 09. Databases: SQL vs NoSQL
Replication 11. Database Replication and Sharding
REST 17. API Design and Gateways
retry storm 21. Designing for Failure
reverse proxy 05. Proxies and Service Communication
reverse proxy cache 08. Content Delivery Networks
Root nameserver 03. Networking Fundamentals
Round Robin 06. Load Balancers
Round-robin DNS 03. Networking Fundamentals
RTP 03. Networking Fundamentals
S3 02. Back-of-Envelope Estimation, 12. Object Storage and Uploads
schema-on-read 09. Databases: SQL vs NoSQL
schema-on-write 09. Databases: SQL vs NoSQL
SDP 18. Real-Time Communication
semi-synchronous 11. Database Replication and Sharding
SendGrid 01. The System Design Process
service mesh 05. Proxies and Service Communication, 17. API Design and Gateways
service registry 05. Proxies and Service Communication
session affinity 06. Load Balancers
SFU 18. Real-Time Communication
shard 11. Database Replication and Sharding
sharding 01. The System Design Process, 11. Database Replication and Sharding
sidecar 05. Proxies and Service Communication
signaling server 18. Real-Time Communication
Signed cookies 12. Object Storage and Uploads
SLA 20. Monitoring and Observability
SLI 20. Monitoring and Observability
Sliding Window Counter 19. Rate Limiting
Sliding Window Log 19. Rate Limiting
SLO 20. Monitoring and Observability
sort key 09. Databases: SQL vs NoSQL
span 20. Monitoring and Observability
SQS 05. Proxies and Service Communication
Squid 05. Proxies and Service Communication
SSD 02. Back-of-Envelope Estimation
SSE 18. Real-Time Communication
SSO 17. API Design and Gateways
Stale-while-revalidate 07. Caching
stateful 04. Scaling and Bottlenecks
stateless 04. Scaling and Bottlenecks
sticky routing 04. Scaling and Bottlenecks
Sticky sessions 18. Real-Time Communication
Storage tiers 12. Object Storage and Uploads
Strong consistency 13. Consistency and CAP Theorem
structured logs 20. Monitoring and Observability
structured process 01. The System Design Process
TCP 03. Networking Fundamentals
Throughput 04. Scaling and Bottlenecks
thundering herd 07. Caching
timeout 21. Designing for Failure
TLD nameserver 03. Networking Fundamentals
Token Bucket 19. Rate Limiting
Traces 20. Monitoring and Observability
Transactional outbox pattern 16. Idempotency and Exactly-Once Delivery
TTL 03. Networking Fundamentals, 07. Caching
TTL jitter 07. Caching
tunable consistency 14. PACELC and Consensus
TURN server 18. Real-Time Communication
Twilio 01. The System Design Process
Two Generals Problem 16. Idempotency and Exactly-Once Delivery
two-phase commit 11. Database Replication and Sharding
UDP 03. Networking Fundamentals
under-fetching 17. API Design and Gateways
UUID 16. Idempotency and Exactly-Once Delivery
Varnish 05. Proxies and Service Communication, 08. Content Delivery Networks
Vector clocks 13. Consistency and CAP Theorem
Version keys 07. Caching
Versioned URLs 08. Content Delivery Networks
Vertical scaling 04. Scaling and Bottlenecks
virtual IP 06. Load Balancers
virtual nodes 11. Database Replication and Sharding
WebRTC 03. Networking Fundamentals, 18. Real-Time Communication
WebSocket 03. Networking Fundamentals
Weighted DNS 03. Networking Fundamentals
Weighted Round Robin 06. Load Balancers
Wide-column stores 09. Databases: SQL vs NoSQL
Write-behind 07. Caching
Write-through 07. Caching
Zipkin 20. Monitoring and Observability
ZooKeeper 05. Proxies and Service Communication, 13. Consistency and CAP Theorem, 14. PACELC and Consensus
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