The Physical Layer
Getting Started
You'll learn the basics of how data is represented, sent, and measured in networking.
How Data Travels
Explore how data travels through physical cables and wireless signals, and the factors that affect signal quality along the way.
Cabling
Explore the different types of network cabling (copper and fiber) and how they're structured, connected, and used in real-world networks.
Hardware
Get familiar with the hardware that makes networks work, from simple to not-so-simple ones.
Network Speed and Standards
Learn what determines network speed, and how physical limits and standards shape that performance.
From Bits to Signals
Learn how raw bits get turned into signals through encoding, modulation, and signal processing.
The Data Link Layer
MAC Addresses
Learn how devices identify each other on a local network, and how these addresses are structured, assigned and used.
How Switches Forward Frames
Find out how switches move data by learning MAC addresses, building forwarding tables, and deciding when to send, flood, or filter frames.
Preventing Loops
Learn why Layer 2 loops are dangerous and how networks prevent them using Spanning Tree and modern techniques.
Framing
Explore how data is packaged into frames for Ethernet and Wi-Fi, and how networks use special frame types to organize traffic.
How Devices Share the Network
Find out how networks let many devices take turns using the same connection, from simple collision methods to modern scheduling and wireless sharing.
Controlling Data Flow
Learn how networks keep data moving smoothly without getting overwhelmed.
Detecting and Fixing Errors
Get familiar with how networks handle transmission errors, from detecting corrupted data to correcting or retransmitting it.
Adding Structure to Data
Learn how networks structure raw data into blocks using techniques that improve reliability and help receivers stay synchronized.t
Linking Layer 2 and Layer 3
Learn how Layer 2 connects to Layer 3, and how it helps organize and identify higher-level network traffic.
Managing Network Links
Find our how network links are established, maintained and closed.
The Network Layer
IP Addressing
Explore how IP addresses work in IPv4 and IPv6, from their structure and behavior to how they're used for routing and communication across networks.
Mapping IP Addresses to Devices
Learn how IP addresses are mapped to physical devices using ARP and NDP, and how systems discover and verify their neighbors.
How Routers Make Decisions
Find out how routers decide where to send packets using routing tables and policies to choose the best path across networks.
How Routers Learn Routes
Explore how routers discover paths across networks using protocols like OSPF and BGP, as well as how those routes are shared and controlled.
When Packets Are Too Big
Learn what happens when packets are too big for the network.
IP Network Protocols
Get to know IP-related protocols that help networks communicate (and provide cool stuff like multicast, tunneling and basic security).
Troubleshooting IP Networks
Learn how to troubleshoot IP networks with some simple tools and techniques all of us use.
Modern IP Networking
Get an overview of how modern networks are designed and connected using NAT, VPNs, SDN, and cloud-based networking.
The Transport Layer
TCP
Get to know TCP - keeps internet connections reliable.
UDP
Get to know UDP - a protocol used when speed matters more than reliability.
Breaking and Rebuilding Data
Learn how data gets split into smaller pieces and put together again (and how we handle errors along the way).
The Session Layer
The Presentation Layer
Structuring and Encoding Data
Find out how data is structured and encoded so systems can understand each other, from character sets to serialization methods.
Making Data Smaller
Explore how compression reduces data size to save bandwidth and improve performance, and how that interacts with security and encryption.
Protecting Data
Learn how data is protected while it moves across networks.
The Application Layer
Web and API Communication
Learn how websites and apps talk to each other, plus how they stay secure and manage access.
How Systems Exchange Messages
Explore how systems exchange messages behind the scenes, from email to event streams.
How Systems Find Each Other
Find out how systems find and identify each other, from DNS to directory services.
Authentication and Authorization
Explore how system verify who you are and decide what you're allowed to do.
Remote Access and Files
Find out how systems access files and shared resources (including other devices) over a network.
Real-Time Communication
Learn how real-time communication works on the internet, from voice and video calls to live sessions.