Vol 4: Computer Networking

The connection succeeds, but the response never arrives. ping gets a reply, but the page will not load. This volume follows messages, state, and timeouts from Ethernet frames, IP, and TCP through HTTP, TLS, DNS, CDNs, and QUIC. Find the failing layer first; the router deserves a break from being rebooted on suspicion.

Prerequisites

• Be able to read and write small programs and distinguish bytes from text. The socket examples build on those skills.
• Be comfortable running terminal commands and have a basic understanding of processes, ports, and file descriptors. Consult Volume 3 for processes and I/O as needed; completing the whole volume is not required.

Coverage

Chapters 1–7 move from layers and sockets to common application protocols. Chapters 8–11 cover links, routing, congestion control, and QUIC. Chapters 12–14 apply those ideas to diagnosis, IPv6, and performance. At each layer, distinguish an observation from a protocol guarantee.

Chapter 1

• 1.1 Network Layers and How a Data Packet Crosses Them

Chapter 2

• 2.1 TCP Socket Lifecycle
• 2.2 Message Boundaries, Deadlines, and Backpressure

Chapter 3

• 3.1 TCP Connection Establishment, Termination, and TIME_WAIT
• 3.2 TCP Sequence Numbers, ACKs, and Flow Control

Chapter 4

• 4.1 HTTP Messages, Methods, and Caching Semantics
• 4.2 HTTP/1.1 Framing and the Minimal Server

Chapter 5

• 5.1 TLS Handshake, Certificate Chains, and Security Boundaries
• 5.2 TLS Secure Client and Fault Diagnosis

Chapter 6

• 6.1 WebSocket Handshake, Frames, and Connection Lifecycle
• 6.2 gRPC Contracts, Streaming RPC, and Failure Boundaries

Chapter 7

• 7.1 DNS Resolution, Records, and Cache Boundaries
• 7.2 CDN Caching, Origin Pulling, and Traffic Routing
• 7.3 Load Balancing Algorithms, Health Checks, and Retry Boundaries

Chapter 8

• 8.1 Ethernet frame, MAC address, and Neighbor Resolution
• 8.2 Ethernet switching, VLANs, and Loop Protection
• 8.3 MTU, IP Fragmentation, and Path MTU Discovery

Chapter 9

• 9.1 IPv4 Headers, CIDR and Longest-Prefix Forwarding
• 9.2 ICMP, ping, and traceroute Evidence Boundaries
• 9.3 NAT, NAPT, and Traversal Boundaries
• 9.4 The Routing Control Plane: RIP, OSPF and BGP

Chapter 10

• 10.1 TCP Congestion Window, Recovery, and ECN
• 10.2 CUBIC, BBR, Pacing and Active Queue Management

Chapter 11

• 11.1 QUIC: Connections, Streams, Loss Recovery and Migration
• 11.2 HTTP/3, QPACK, Discovery and Deployment

Chapter 12

• 12.1 From Symptoms to Evidence: Layered Network Diagnostics
• 12.2 Packet Capture and Protocol Analysis: Choose Your Observation Point, Then Interpret the Data
• 12.3 Repeatable Network Diagnostics Experiments

Chapter 13

• 13.1 IPv6 Data Packets, Addresses, and Subnets
• 13.2 ICMPv6, NDP, and Address Autoconfiguration
• 13.3 Dual Stack, Happy Eyeballs, and IPv6-Only Transition

Chapter 14

• 14.1 Network Performance Measurement and Bottleneck Identification
• 14.2 Transport Performance: RTT, Windows, Loss, Queues, and Connection Reuse
• 14.3 HTTP, Caching, CDN, and Capacity Optimization

Outcomes

• Design message framing, timeouts, and backpressure for a TCP application, and explain its connection lifecycle.
• Narrow down a fault using DNS, TLS, HTTP, and transport evidence, including what a packet capture can establish.
• Use RTT, windows, loss, caching, and connection reuse to decide which layer needs performance work.

How to use this map

Read in order for a first pass, and run the small programs in Chapters 2 and 4 early. For troubleshooting, start with Chapter 12 to choose an observation point, then revisit the relevant protocol. For performance work, use Chapter 14 to establish a baseline. Capture only traffic you are authorized to inspect, and account for how capture location and encryption limit what you can see.