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Networking Foundations

Complete beginners who want to understand how computer networks work.

Build a practical mental model for how modern networks move data.

6 modules29 lessons~11 hours

Modules and lessons

Computer Network Basics

Learn the essential vocabulary, devices, addresses, and layered models before studying how data moves.

9 lessons

  1. Introduction to Computer Networks and Network Devices

    Describe how a computer works, define a computer network, and identify end and intermediary devices.

    Estimated time: 5–15 minFree

  2. Hosts, Clients and Servers

    Recognize hosts and explain how applications can act as clients, servers, or both.

    Estimated time: 10–20 minFree

  3. Hubs

    Explain that a hub repeats an incoming signal to its other ports and why hubs are now mostly historical.

    Estimated time: 5–15 minFree

  4. Bridges

    Explain how bridges introduced segmentation and basic filtering before modern switches.

    Estimated time: 5–15 minFree

  5. Switches

    Explain how switches connect local devices and associate devices with ports at an introductory level.

    Estimated time: 5–15 minFree

  6. Routers

    Explain how routers connect different IP networks and act as default gateways.

    Estimated time: 5–15 minFree

  7. Logical and Physical Addressing

    Distinguish MAC and IP address roles and recognize their basic formats.

    Estimated time: 10–20 minFree

  8. OSI and TCP/IP Models

    Relate common network tasks to the OSI and TCP/IP models.

    Estimated time: 15–25 minFree

  9. Computer Network Basics Final Quiz

    Check your understanding of the concepts introduced throughout Computer Network Basics.

    Estimated time: 5–15 minFree account

Ethernet, Switching and Local Networks

Understand frames, local delivery, switching decisions, and broadcast boundaries.

6 lessons

  1. Cables, Fibre, Wireless and Network Connections

    Choose an appropriate connection medium and explain duplex, speed, signal, and link state at a beginner level.

    Estimated time: 15–25 minFree

  2. Unicast, Broadcast and Multicast Communication

    Identify a transmission's delivery scope and predict which interfaces receive, accept, or forward it.

    Estimated time: 15–25 minFree

  3. Ethernet Frames and MAC Addresses

    Read the purpose of core Ethernet fields and distinguish unicast, broadcast, and multicast destinations.

    Estimated time: 20–30 minFree

  4. How Switches Learn and Forward

    Build and use a MAC address table to predict forwarding, filtering, and flooding.

    Estimated time: 20–30 minFree

  5. ARP and Local Delivery

    Explain how IPv4 nodes resolve a local next-hop IP address to a MAC address.

    Estimated time: 20–30 minFree

  6. VLANs, Access Ports and Trunks

    Explain why VLANs create separate broadcast domains and how access and trunk links carry them.

    Estimated time: 20–30 minFree

IP Addressing and Routing

Learn addressing, subnetting, routing choices, and network control evidence.

5 lessons

  1. IPv4 Addressing

    Read dotted-decimal addresses and prefixes and distinguish network, host, private, public, loopback, link-local, and documentation ranges.

    Estimated time: 20–30 minFree

  2. Subnetting Fundamentals

    Calculate network boundaries, usable ranges, broadcast addresses, and host capacity for common IPv4 prefixes.

    Estimated time: 20–30 minFree

  3. IPv6 Fundamentals

    Read and shorten IPv6 addresses and explain prefixes, link-local/global addresses, multicast, Neighbor Discovery, SLAAC, and default-router discovery.

    Estimated time: 20–30 minFree

  4. Routing, Routing Tables and Default Routes

    Read a basic routing table and choose a route using longest-prefix match and administrative/metric concepts at the appropriate depth.

    Estimated time: 20–30 minFree

  5. ICMP, Ping and Path Discovery

    Use ICMP as control/error evidence and explain what ping and traceroute do and do not prove.

    Estimated time: 15–25 minFree

Transport and Application Services

Explore transport behavior and the services applications rely on.

5 lessons

  1. TCP: Reliable Transport

    Trace TCP connections, byte-stream reliability, receive windows, MSS, window scaling, SACK, and fast retransmission.

    Estimated time: 35–45 minFree

  2. UDP: Datagrams and Ports

    Read UDP datagrams, trace port-based delivery, and diagnose replies, ICMP errors, and silence without assuming reliability.

    Estimated time: 15–25 minFree

  3. DHCP and Automatic Address Configuration

    Trace IPv4 DHCP acquisition, renewal, and relay behavior while reading exact packet, port, address, and option evidence.

    Estimated time: 30–40 minFree

  4. DNS and Name Resolution

    Trace recursive name resolution and distinguish stub resolver, recursive resolver, authoritative server, common records, caching, and response codes.

    Estimated time: 20–30 minFree

  5. HTTP, HTTPS, TLS and Essential Network Services

    Trace and troubleshoot HTTP/HTTPS, SSH/Telnet, email, file transfer, NTP, and SNMP using ports, message fields, security choices, and packet evidence.

    Estimated time: 50–60 minFree

NAT and Internet Communication

Trace address translation through an end-to-end internet exchange.

3 lessons

  1. Access Points, Modems, ONTs and Firewalls

    Explain where common edge devices fit and distinguish access, conversion, routing, and security roles.

    Estimated time: 15–25 minFree

  2. NAT, PAT and the Complete Internet Packet Journey

    Trace IPv4 address and port translation in both directions, read translation state, and diagnose failed return paths.

    Estimated time: 30–40 minFree

  3. A Packet’s First Journey Through a Small Network

    Narrate an end-to-end exchange using the concepts from Lessons 1–8.

    Estimated time: 20–30 minFree

Packet Analysis and Troubleshooting

Apply evidence-driven, layer-aware troubleshooting to network faults.

1 lesson

  1. Systematic Network Troubleshooting Capstone

    Apply a repeatable, layer-aware troubleshooting method and communicate evidence, scope, hypothesis, test, result, and next action.

    Estimated time: 40–50 minFree