Computer Networks, from packets to the web
Understand what happens between clicking a link and seeing a page. Build the vocabulary, calculate a subnet, and diagnose failures one layer at a time.
How to learn
Read each lesson, work through its example, then answer its practice check. The completion marker stays in this browser; you do not need an account. You can jump to any lesson at any time.
Course roadmap
Start with local and end-to-end communication, then put the pieces together in the capstone.
Networks, Packets & Delay
Explain how a message crosses a network and calculate simple transmission delay.
Open lesson →02Layers & Encapsulation
Trace a request from application data to a link frame and back.
Open lesson →03Signals, Media & Bandwidth
Choose an appropriate medium and distinguish throughput from capacity.
Open lesson →04Ethernet, Switching & ARP
Explain local forwarding and how IPv4 finds a neighbor's link address.
Open lesson →05IPv4, CIDR & Subnets
Compute network ranges and usable host addresses for typical IPv4 subnets.
Open lesson →06Routing & Forwarding
Use longest-prefix match and tell routing decisions from packet forwarding.
Open lesson →07TCP, UDP & Ports
Compare TCP and UDP and identify the role of ports, reliability and flow control.
Open lesson →08DNS, DHCP & NAT
Follow address configuration, name resolution and common home-router translation.
Open lesson →09HTTP, HTTPS & TLS
Describe a web request, response status and what TLS protects.
Open lesson →10Wi-Fi & Network Security
Identify wireless constraints and basic defenses for real network use.
Open lesson →11Troubleshooting a Network
Use a systematic path from local interface to application.
Open lesson →12Capstone: Trace a Web Request
Combine layers and calculate, explain and diagnose a complete browser journey.
Open lesson →Keep practicing
After the capstone, use the Placement practice area for interview-style questions. Each lesson links to a relevant protocol specification for deeper reading.