Networking Fundamentals: How Networks and the Internet Work

Understand how data crosses networks and the internet, from cables and switches to IP, TCP and DNS, and troubleshoot a connection yourself.

Beginner · Networking · about 9.5 hours · 4 modules · certificate on completion

Taught by Sekouù Camàra, Mouhamadouù Bâ, AI Learning Companions.

About this course

How does a message get from your laptop to a server on the other side of the world, and what do you check when it doesn't? This course explains how networks and the internet work, from the cables and switches in a building to the addresses, protocols and names that carry a web page to your screen. You'll meet the devices networks are made of, the OSI and TCP/IP models, Ethernet and MAC addresses, IP addresses and default gateways, TCP, UDP and ports, and what DNS and HTTP do when a page loads.

You'll learn it hands-on. You'll build networks in Cisco Packet Tracer and step through them packet by packet in Simulation mode, look inside real frames with Wireshark, and test your own computer's connection with ping, traceroute and ipconfig or ip. Every module ends with a lab your instructor reviews, and the course ends with a project in which you build, test and document a network end to end. The course follows the Network Fundamentals section of Cisco's published CCNA (200-301) exam topics, making it a good first step towards that exam.

What you'll learn

  • Describe what networks are made of, from endpoints, switches and routers to access points and firewalls, and how they're cabled
  • Explain how data is wrapped and delivered, using the OSI and TCP/IP models, Ethernet frames and MAC addresses
  • Explain how IP addresses, subnet masks and default gateways get packets from one network to another
  • Compare TCP and UDP, and follow DNS and HTTP through the loading of a web page
  • Build and test small networks in Cisco Packet Tracer, and watch real traffic in Wireshark
  • Troubleshoot a connection step by step with ping, traceroute and tracert, and ipconfig or ip

Skills you'll gain

Network fundamentals, OSI and TCP/IP models, Ethernet and MAC addresses, IPv4 addressing basics, TCP and UDP, DNS and HTTP, Network troubleshooting, Cisco Packet Tracer, Wireshark

Tools

Cisco Packet Tracer, Wireshark

Before you start

None: this course starts from zero. You need a Windows, macOS or Linux computer that can run Cisco Packet Tracer (free with a Cisco Networking Academy account) and Wireshark (free from wireshark.org), and that you're allowed to install software and capture traffic on.

Aligned with: Cisco CCNA (200-301) exam topics: Network Fundamentals

Modules

  1. What networks are made of

    Meet the devices a network is built from, the shapes networks are built in and the cables that join them, then build your first network in Cisco Packet Tracer.

    • Endpoints, switches, routers and the rest (10 min)
    • Network topologies and designs (10 min)
    • Cables, connectors and interface problems (12 min)
    • Hands-on lab: Build and test your first network

  2. Layers, Ethernet and switching

    See how data is wrapped in layers on its way across a network, what's inside an Ethernet frame, and how a switch learns where every device is.

    • The OSI and TCP/IP models (12 min)
    • Ethernet frames and MAC addresses (12 min)
    • How switches learn, flood and forward (12 min)
    • Hands-on lab: Watch a switch learn and flood

  3. IP, transport and applications

    Follow a packet from one network to another through a default gateway, see how TCP and UDP deliver data to the right application, and trace DNS and HTTP as a web page loads.

    • IP addresses, subnet masks and default gateways (12 min)
    • TCP, UDP and port numbers (12 min)
    • DNS and HTTP: loading a web page (14 min)
    • Hands-on lab: Follow a web page request in Packet Tracer

  4. Troubleshooting connectivity

    Find out why something can't connect, methodically: check a computer's IP settings, test the path with ping and traceroute, and watch the tests themselves in Wireshark.

    • A method for troubleshooting (10 min)
    • Testing the path: ping and traceroute (12 min)
    • Checking a computer's IP settings (12 min)
    • Hands-on lab: Diagnose your own connection

Project: Build, test and document a network, end to end

Build a network in Packet Tracer for a small community library and prove it works from the cable up, then test and document a real network you use. In Packet Tracer, a 2911 router joins two LANs, each with a 2960 switch: a staff LAN, 192.168.10.0/24, with two PCs, and a public LAN, 192.168.20.0/24, with two PCs, a DNS server at 192.168.20.53 and a web server at 192.168.20.80. The router uses the first address on each LAN. The web server's home page names the library, and the DNS server maps www.library.test to the web server. Show that every PC can reach the web server by name, step through one page load in Simulation mode, and explain each event with the OSI and TCP/IP models. Then, on your own computer and network, record the IP settings, test the connection with ping, traceroute or tracert and nslookup, and capture the tests in Wireshark. Finish with a one-page summary comparing the two networks, and a plan for helping someone who can't open a website.

Part of

Cisco, CCNA, Cisco IOS and Cisco Packet Tracer are trademarks of Cisco Systems, Inc. This course is independent: Cisco hasn't made or endorsed it, and it doesn't give you a Cisco certification.

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