Computer Networking Guide for Developers

Every web app depends on the network, and most hard bugs hide there. This guide goes from packets and addresses to TLS, load balancers and real-time connections, one layer at a time.

Each lesson uses real tools such as curl, dig, ss and tcpdump, and the output you see is the output we got.

Who it is for: Developers who want to understand what happens between the browser and the server, and candidates for back-end and DevOps roles who get networking questions.

9 lessons · Published by Jainik · Last updated

1. The basics

  1. 1. Networking for Developers · 13 min
    How the Internet Works: Layers, Packets and Addresses

    The layer models, what a packet is, MAC, IP and ports, and following one request from your laptop to a server.

  2. 2. Networking for Developers · 14 min
    IP Addresses, Subnets, NAT and Routing

    IPv4 and IPv6, CIDR notation worked by hand, private ranges, NAT, routing tables and how a packet finds its way.

2. Transport and names

  1. 3. Networking for Developers · 16 min
    TCP and UDP: Connections, Reliability and Congestion

    The three-way handshake, sequence numbers, retransmission, flow and congestion control, UDP, and when each is used. Captured with real packet tools.

  2. 4. Networking for Developers · 14 min
    DNS: How Names Become Addresses

    Resolvers, root and authoritative servers, record types, TTL and caching, and debugging DNS with dig.

3. The web protocols

  1. 5. Networking for Developers · 15 min
    HTTP/1.1, HTTP/2 and HTTP/3

    Requests and responses on the wire, keep-alive, head-of-line blocking, multiplexing, QUIC, and what changes for you as a developer.

  2. 6. Networking for Developers · 15 min
    TLS and Certificates: How HTTPS Really Works

    The handshake in plain words, certificates and chains, Let's Encrypt, mTLS, and the errors you will meet.

4. Traffic in production

  1. 7. Networking for Developers · 14 min
    Load Balancers, Proxies, CDNs and Firewalls

    Layer 4 and layer 7 balancing, reverse and forward proxies, CDNs, caching at the edge, and firewalls and security groups.

  2. 8. Networking for Developers · 14 min
    WebSockets, Server-Sent Events and Real-Time Networking

    Polling versus long polling, WebSockets, SSE, scaling real-time connections, and a working example of each.

5. Debugging and interviews

  1. 9. Networking for Developers · 16 min
    Debugging Network Problems and Networking Interview Questions

    curl, dig, ss, tcpdump and Wireshark basics, a troubleshooting checklist, and interview questions with model answers.

More reading orders are on the guides page, and every series is listed on the home page.