# Networks
All Networks notes →1 — Why Computer Networks Matter
Why computer networks exist and matter: the evolution of networking, internet architecture, client-server and peer-to-peer models, and how distributed systems and cloud networking build on top of them.
2 — Data Communication Basics
The core data-communication metrics — signals, bandwidth, latency, throughput, jitter, packet loss, serialization delay, and propagation delay — that every later performance discussion depends on.
4 — Network Devices
What NICs, repeaters, hubs, bridges, switches, routers, gateways, firewalls, load balancers, and reverse proxies each actually do, and where each sits in a real network path.
1 — Ethernet
Ethernet framing, MAC addressing, MTU and jumbo frames, and VLANs/trunk ports as the mechanics of a single local network segment.
2 — ARP
How ARP resolves IP addresses to MAC addresses, plus gratuitous ARP, the ARP cache, and proxy ARP.
3 — Switching
Learning switches, CAM tables, broadcast vs. collision domains, and how Spanning Tree Protocol prevents loops.
1 — IPv4
The IPv4 header, CIDR notation, subnetting and supernetting, reserved address ranges, and the public-vs-private IP distinction.
2 — IPv6
The IPv6 header and address types, and how Stateless Address Autoconfiguration and Neighbor Discovery replace IPv4's DHCP/ARP mechanics.
3 — Routing
Static vs. dynamic routing, how routing tables and longest-prefix-match actually pick a next hop, and the role of a default gateway.
4 — Routing Protocols
RIP, OSPF, and BGP as routing protocols at different scales, plus ECMP and how routing actually holds the internet together.
1 — UDP
UDP's datagram model and reliability trade-offs, and why DNS, VoIP, and gaming traffic choose it over TCP.
2 — TCP Fundamentals
The TCP three-way handshake and four-way termination, the TCP header, sequence numbers, and ACKs that make reliable delivery possible.
3 — Reliable Transmission
How TCP achieves reliability in practice — sliding window, flow control, congestion control, slow start, AIMD, and fast recovery.
4 — TCP Optimization
Production TCP tuning: the Nagle algorithm, delayed ACK, keep-alive, window scaling, and TCP Fast Open.
5 — QUIC
Why QUIC exists, what it changes by moving transport onto UDP, and how it enables HTTP/3, connection migration, and stream multiplexing.
1 — DNS Fundamentals
Name resolution end to end: recursive resolvers, authoritative servers, and the root server hierarchy behind every DNS lookup.
2 — DNS Records
The DNS record types — A, AAAA, CNAME, TXT, NS, MX, SRV, PTR — and what each one actually resolves.
3 — DNS Performance
TTL and caching behavior, plus split-horizon DNS, GeoDNS, and anycast DNS as the levers for DNS-driven performance and routing.
1 — HTTP Fundamentals
The HTTP request lifecycle — methods, status codes, headers, and cookies — as the foundation every later chapter in this Part builds on.
3 — REST
REST resource design, idempotency, pagination, versioning, and content negotiation as the conventions behind most production HTTP APIs.
4 — GraphQL
GraphQL's query, mutation, and subscription model, and the performance trade-offs it makes relative to REST.
6 — WebSockets
The WebSocket upgrade handshake and persistent, full-duplex connections that make real-time systems possible over HTTP.
1 — Cryptography Fundamentals
Symmetric and asymmetric encryption, hashing, and HMAC as the cryptographic primitives every later security chapter depends on.
3 — HTTPS
Certificate validation, HSTS, OCSP, and session resumption as the mechanics that turn TLS into HTTPS in practice.
4 — Authentication Protocols
OAuth2, OIDC, JWT, SAML, and Kerberos as the authentication protocols that show up repeatedly in distributed-systems interviews.
5 — Network Security
VPNs, IPSec, WAFs, IDS/IPS, and DDoS protection as the network-level security controls layered on top of TLS.
1 — Virtual Networking
VPCs/VNets, subnets, route tables, and security groups as the building blocks of a cloud network.
2 — Kubernetes Networking
The Kubernetes networking model — pod network, CNI, kube-proxy, Services, Ingress, and the Gateway API.
3 — Service Mesh
Istio, Linkerd, and Envoy as service mesh implementations, and how sidecars and mTLS turn a mesh into a security and traffic-control layer.
4 — Load Balancing
L4 vs. L7 load balancing, round robin, least connections, consistent hashing, and health checks as the mechanics behind traffic distribution.
5 — CDN
Edge nodes, cache invalidation, Cache-Control, and origin shield as the mechanics behind a CDN's performance and cost story.
1 — Network Performance
Bandwidth vs. latency, bufferbloat, tail latency, and head-of-line blocking as the performance concepts that separate a fast network from a merely working one.
2 — Connection Management
Connection pools, keep-alive, timeouts, retries, and circuit breakers as the client-side levers for managing unreliable network connections.
3 — Compression
gzip, Brotli, and HTTP compression as the payload-optimization techniques that trade CPU for bandwidth.
4 — Caching
Browser cache, CDN cache, reverse-proxy cache, and application cache as the layered caching strategy behind most low-latency systems.
5 — Network Benchmarking
iperf, wrk, k6, Vegeta, and tc as the tools used to actually measure and simulate network performance.
1 — Packet Analysis
tcpdump and Wireshark as the tools for capturing and reading raw packets and TCP streams.
2 — Linux Networking
The Linux networking command-line toolkit — ss, netstat, ip, ifconfig, route, traceroute, and ping — for diagnosing a network from the box itself.
3 — DNS Debugging
dig, nslookup, and host as the tools for debugging DNS resolution problems.
4 — HTTP Debugging
curl, Postman, and HTTPie as the tools for debugging HTTP requests and responses directly.
5 — Kubernetes Network Debugging
kubectl exec, ephemeral containers, BusyBox, Network Policies, and Cilium monitor as the toolkit for debugging networking inside a Kubernetes cluster.
1 — RPC Systems
The RPC call lifecycle, serialization, and timeouts as the networking concerns underneath every remote procedure call.
2 — Message Brokers
Kafka, RabbitMQ, NATS, and Pulsar as message brokers, and how each handles the networking side of asynchronous messaging.
3 — Event Streaming
Partitions, consumer groups, and delivery guarantees as the mechanics behind event-streaming systems built on top of message brokers.
4 — CAP and Networking
How network partitions force the availability-vs-consistency trade-off the CAP theorem describes.
5 — Cross-Region Communication
Replication, WAN latency, and multi-region design as the networking concerns specific to systems that span regions.
1 — Common MAANG Networking Questions
Recurring MAANG networking interview questions — why TCP over UDP, HTTP/2 vs HTTP/3, why TLS needs certificates, what happens when you type google.com, and why latency matters.
2 — Production Incidents
DNS outages, BGP leaks, SYN floods, TLS expiration, and network partitions as the production incident patterns worth knowing cold.
3 — Cloud Networking Case Studies
How Netflix, Google, Meta, Amazon, and Cloudflare have approached networking at planet scale, and the transferable lessons across them.
4 — Networking Design Interviews
API gateway, CDN, global load balancer, edge computing, and service mesh as the recurring networking system-design interview prompts.
5 — Review & Cheat Sheets
A consolidated review across TCP flags, HTTP status codes, the TLS handshake, DNS resolution, the OSI model, and CIDR — the interview quick-reference for this entire book.
1 — Common Ports
A reference table of common ports across the 20–65535 range and the services conventionally bound to them.
10 — Wireshark Filters
A cheat sheet of commonly used Wireshark display filters for isolating traffic during packet analysis.
11 — tcpdump Cheat Sheet
A cheat sheet of common tcpdump invocations and filter expressions for capturing traffic from the command line.
12 — curl Cheat Sheet
A cheat sheet of common curl flags and invocations for debugging HTTP requests from the command line.
13 — Linux Networking Commands
A consolidated command reference for Linux networking tools — ss, ip, netstat, route, traceroute, and ping.
14 — Kubernetes Networking Commands
A consolidated command reference for debugging Kubernetes networking — kubectl exec, ephemeral containers, and Cilium monitor.
15 — Cloud Networking Terminology
A glossary of cloud networking terminology — VPC, VNet, NSG, peering, and related terms — for quick lookup across cloud providers.
16 — Common Interview Pitfalls
A list of common networking interview pitfalls and the misconceptions behind each one.
2 — HTTP Status Codes
A reference table of HTTP status codes grouped by class, with what each one actually signals.
3 — TCP Flags
A reference table of the TCP header's control flags — SYN, ACK, FIN, RST, PSH, URG — and what each means in a packet capture.
4 — ICMP Message Types
A reference table of ICMP message types and codes, including the ones behind ping and traceroute.
5 — CIDR Cheat Sheet
A CIDR notation cheat sheet mapping prefix length to subnet size and usable host count.
6 — IPv4 Reserved Ranges
A reference table of reserved and special-use IPv4 address ranges — private ranges, loopback, link-local, and multicast.
7 — IPv6 Address Types
A reference table of IPv6 address types — unicast, multicast, anycast, link-local, and unique local — and how to recognize each.
8 — TLS Cipher Suites
A reference table of TLS cipher suites and what their naming convention actually encodes.
9 — DNS Record Types
A consolidated reference table of DNS record types for quick lookup alongside Part IV's DNS chapters.
Computer Networks
A book-shaped table of contents for computer networking, from first principles to production systems: Ethernet through IP, TCP/UDP/QUIC, DNS, the HTTP ecosystem, security, cloud/Kubernetes networking, performance engineering, observability/debugging, and distributed-systems networking — cross-linking existing kubernetes/sre/system-design/tech notes instead of duplicating them.