Networking for Beginners

01

What Is a Network?

Understand what a computer network is, what it is made of, how data moves through it, and the basic terms the rest of this course builds on.

~19 min 02

The OSI Model

Learn the seven layers of the OSI model, what each one does, how data is wrapped as it travels, and how to use the layers to find network problems.

~21 min 03

IP Addresses

Understand what IP addresses are, how IPv4 and IPv6 are written, why the numbers stop at 255, and how public and private addresses differ.

~21 min 04

Subnetting

Learn what subnets are, how to read a subnet mask and CIDR notation, and how to work out usable hosts, network addresses and broadcast addresses.

~31 min 05

MAC Addresses and ARP

Learn what MAC addresses are, how they differ from IP addresses, how ARP finds a MAC address, and how switches use MAC addresses to forward frames.

~21 min 06

TCP, UDP and Ports

Learn the two main transport protocols, how TCP makes delivery reliable, when UDP is the better choice, and how port numbers send data to the right program.

~25 min 07

DNS

Learn how DNS turns names like example.com into IP addresses, what happens when you type a URL, what DNS records are, and how to query and troubleshoot DNS yourself.

~27 min 08

Routers and NAT

Learn how routers move traffic between networks, what routing tables and default gateways are, how TTL stops loops, and how NAT lets many devices share one public address.

~29 min 09

DHCP

Learn how DHCP hands out IP addresses and other network settings automatically, the four-step DORA process, leases, address pools and reservations.

~20 min 10

HTTP and HTTPS

Learn how HTTP requests and responses work, what status codes mean, how cookies give websites a memory, and how HTTPS protects traffic with TLS and certificates.

~27 min 11

Firewalls and VPNs

Learn what firewalls do, how rule lists work, the difference between stateless and stateful filtering, how to use ufw on Linux, and what a VPN adds.

~26 min 12

Troubleshooting Step by Step

Learn a calm, step-by-step method to diagnose network problems using the layers, a handful of commands, and a few habits that save time.

~29 min 13

WiFi and Wireless

Learn how WiFi works, what the standards and frequency bands mean, how wireless security differs between WEP, WPA2 and WPA3, and why WiFi is sometimes slow.

~22 min 14

Network Tools You Should Know

Meet the everyday command-line tools for testing and analysing networks, and learn which one to use for which question: ping, traceroute, dig, ss, ip, curl, nmap and Wireshark.

~29 min 15

VLANs and Segmentation

Learn how VLANs split one physical network into separate logical ones, why that improves security and performance, how access and trunk ports work, and how traffic moves between VLANs.

~21 min 16

Cloud Networking Basics

Learn how networking works in the cloud: VPCs, public and private subnets, gateways, route tables, security groups, load balancers and how to connect the cloud to your own network.

~25 min 17

Protocols and Ports Cheat Sheet

A practical reference to the network protocols and port numbers you will meet most often, grouped by the layer they work at, with a note on which ones are encrypted.

~19 min 18

What to Learn Next

You have finished the networking fundamentals. See where to go next if you want to become a network engineer, a security professional, a cloud engineer or a Linux administrator.

~18 min