Network Fundamentals

Learn how networks work, from the cables and devices to IP addresses, DNS and troubleshooting.

For complete beginners. No experience needed. When you finish, you're ready for the CCNA course.

Units

1. Unit 1
   Networking Basics

   What a network is, why people build them, the kinds of network you meet, and the shapes they take.

   4 lessons
2. Unit 2
   Network Devices

   The boxes that make a network work: what each one does, where it sits, and how they differ.

   8 lessons
3. Unit 3
   Network Models

   The OSI and TCP/IP models, and how data is wrapped and unwrapped on its way across a network.

   3 lessons
4. Unit 4
   Ethernet and Cabling

   How Ethernet frames and MAC addresses work, how a switch learns, and the cables and speeds underneath.

   9 lessons
5. Unit 5
   IP Addressing Basics

   What an IP address is, public and private ranges, the subnet mask, the default gateway, and IPv6.

   6 lessons
6. Unit 6
   ARP and Local Communication

   How devices find each other's MAC addresses, and how local and remote communication begins.

   3 lessons
7. Unit 7
   TCP, UDP and Ports

   How data reaches the right application, reliably with TCP or quickly with UDP.

   20 lessons
8. Unit 8
   Core Network Services

   The services every network relies on: DNS for names, DHCP for addresses, NAT for internet access.

   4 lessons
9. Unit 9
   ICMP and Network Testing

   The messages behind ping and traceroute, and how to read what they tell you.

   3 lessons
10. Unit 10
    Network Traffic Types

    Unicast, broadcast and multicast: who receives a message, and how far it travels.

    2 lessons
11. Unit 11
    Wireless Fundamentals

    How Wi-Fi works, the frequency bands it uses, and how it is secured.

    3 lessons
12. Unit 12
    Network Security Fundamentals

    The core ideas of security, and the firewalls, VPNs and segmentation that put them into practice.

    4 lessons
13. Unit 13
    Complete Packet Flow

    Everything together: follow real packets step by step, from one PC to another and out to the internet.

    3 lessons
14. Unit 14
    Network Troubleshooting

    A step-by-step method and the Windows and Linux commands to find what's broken.

    10 lessons
15. Unit 15
    Modern Networking Introduction

    A first look at the networks inside data centres and public clouds.

    2 lessons