Introduction to Computer Networking
Coursera
One-hour NVIDIA course on Coursera introducing why networks exist, the OSI model, the TCP/IP suite, Ethernet forwarding, and basic data center design. Completing it gives you the vocabulary needed before studying switching or routing in depth.
More resources on Networking
Computer Networking: A Top-Down Approach
University textbook that presents networking from the application layer downward, covering HTTP, DNS, TCP congestion control, routing algorithms, link-layer protocols, and wireless. Working through it gives you a principled model of how internet traffic actually moves.
r/networking
Reddit community for enterprise network engineers discussing routing, switching, BGP, firewalls, wireless, vendor equipment and career questions. Readers can see how practitioners troubleshoot real outages, compare hardware and design choices, and get answers to specific configuration problems.
Professor Messer Network+
Free video training course covering the full CompTIA Network+ N10-008 exam objectives: cabling, IP addressing, routing, switching, wireless, and troubleshooting. Watching it prepares you to sit the certification exam without paying for commercial courseware.
Practical Networking
Free website with diagrams and explanations of networking concepts, frequently recommended on Reddit.
Introduction to Networks
Learn networking basics with Cisco's Introduction to Networks course. Explore fundamental concepts and build a foundation for your IT career!
Practical Networking
Free article series on how packets actually traverse a network, plus deep treatments of ARP, NAT, access control lists, VLANs, and cryptography. Each series builds sequentially toward a working mental model rather than memorised commands.