Aisha R.
Sample Free and very well structured
Short lessons, real commands and no jargon without explanation. Recommended it to my whole support team.
Networking fundamentals: TCP/IP, DNS and how the internet works
Understand IP addressing, TCP and UDP, routing, NAT, DNS and HTTPS, and troubleshoot connections with ping, traceroute, dig and curl
Created by Luka Janelidze
- Updated August 2026
- English
- Beginner
What you will learn
- Explain how a web request travels from a browser to a server and back
- Describe the TCP/IP layers and what each one does
- Read IP addresses and subnet masks and identify private ranges
- Explain how TCP and UDP differ and what ports are for
- Describe how DHCP, ARP, routing and NAT work together
- Trace DNS resolution and read common DNS records
- Troubleshoot connections with ping, traceroute, dig and curl
Course content
How networks really work
Your local network
- Article: Ethernet and MAC addresses 9 min
- Article: ARP: finding neighbours 8 min
- Article: Switches and Wi-Fi 9 min
- Article: DHCP: getting an address automatically 9 min
Crossing the internet
- Article: Routing and the default gateway 10 min
- Article: NAT and private networks 9 min
- Article: IPv6 essentials 10 min
- Article: Traceroute and the path to a server 8 min
Names and the web
- Article: How DNS resolution works 10 min
- Article: DNS record types 9 min
- Article: HTTP and HTTPS 10 min
- Article: TLS and certificates 9 min
Troubleshooting with confidence
- Article: ping and interface checks 8 min
- Article: Diagnosing DNS with dig and nslookup 9 min
- Article: Testing services with curl and nc 9 min
- Article: A methodical troubleshooting process 10 min
- Article: Firewalls and blocked traffic 8 min
Where to go next
- Article: Home, office and data centre networks 8 min
- Article: Networking in the cloud 9 min
- Quiz: Final check 6 min
Requirements
- A computer with Windows, macOS or Linux
- No networking knowledge required
Description
Every developer, IT professional and curious computer user depends on networks, yet many treat them as a black box. When a site will not load, an API times out or a home printer disappears, they guess. This free course opens the box and explains, step by step, what actually happens between two computers.
What you will learn
We follow a single request, opening a web page, from your laptop to a server on the other side of the world and back. Each section zooms in on one part of that journey.
- The layered model that organises networking: OSI and TCP/IP
- IP addresses, subnet masks and private versus public addresses
- Ports, TCP connections and when UDP is used instead
- Ethernet, MAC addresses, ARP, switches, Wi-Fi and DHCP
- Routing, default gateways, NAT and the basics of IPv6
- DNS resolution and the most common record types
- HTTP, HTTPS and TLS certificates
- A calm, methodical approach to troubleshooting
Hands on practice
You will use the command line tools that network engineers rely on: ping, traceroute, ip or ipconfig, nslookup and dig, and curl. All are free and already available or easy to install on Windows, macOS and Linux. Each lesson includes small experiments you can run on your own network.
Who it is for
Developers, IT support staff, students and anyone preparing for entry level networking or IT certifications. No prior networking knowledge is needed. By the end, you will be able to explain how the internet works and diagnose common connection problems with confidence.
Who this course is for
- Developers who want to understand the networks their code runs on
- IT support staff and students starting in networking
- Anyone preparing for entry level IT or networking certifications
Instructor
Luka Janelidze
Network engineer teaching TCP/IP, routing and troubleshooting with real tools and configs
- 4.3 instructor rating
- 21 reviews
- 8,940 students
- 3 courses
- Sample
I have worked as a network engineer in campus and data centre environments, designing addressing plans, configuring switches and routers and spending more hours than I can count reading packet captures.
I teach networking from first principles and always connect theory to something you can see: a ping, a traceroute, a Wireshark trace or a running config. You will build labs in free tools like Cisco Packet Tracer and GNS3, and practise on your own machine with the command line.
My courses help developers, IT staff and students preparing for entry level certifications understand what actually happens between two hosts, and give them a calm, methodical way to fix things when the network breaks.
Student reviews
Giorgi M.
Sample The ten step journey is brilliant
Following one web request through the whole course made everything connect. I finally understand what my router does.
Hannah P.
Sample Perfect for developers
I build web apps and never knew what happened below HTTP. The curl and dig lessons are now part of my debugging routine.
Yara S.
Sample DNS finally makes sense
The resolution walkthrough and record types lesson solved a mail problem I had for weeks.
Samuel A.
Sample Clear subnetting basics
The /24 explanation was the first one that made sense to me. I would like more subnetting practice, which the follow up course covers.
Lena K.
Sample Great for IT support
The troubleshooting method helped me fix problems faster at work. Good balance of theory and commands.
Ivan D.
Sample Some repetition across sections
Solid content, though a few concepts are repeated. Still the best free networking intro I have found.
Oscar N.
Sample Helped with my certification study
Made the OSI model feel practical rather than something to memorise.
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