Module 2
Layers and Protocols
The vocabulary everything else in this path assumes - which layer a thing belongs to, what changes as a packet crosses a router, and how a port number picks an application.
4 activities~32 min
In this module
- Name the OSI layers and map them onto the TCP/IP stack in use
- Explain what each layer adds to a packet and what a router rewrites
- Compare TCP and UDP, and identify the common well-known ports
Activities
Lesson
Layers - the OSI and TCP/IP models
Seven layers, four layers, and why people use both sets of names.
9 min
Lesson
Encapsulation - how data crosses the layers
What each layer wraps, and why IP addresses stay put while MAC addresses change at every hop.
8 min
Lesson
TCP, UDP and port numbers
Two ways to deliver, and what decides which application receives data.
9 min
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Curriculum topics
Each topic page lists every lesson, quiz and hands-on lab that covers it, plus how it maps onto the CCNA and Network+ blueprints.