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.
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
Layers - the OSI and TCP/IP models
Seven layers, four layers, and why people use both sets of names.
Encapsulation - how data crosses the layers
What each layer wraps, and why IP addresses stay put while MAC addresses change at every hop.
TCP, UDP and port numbers
Two ways to deliver, and what decides which application receives data.
Knowledge check - layers and protocols
Placing things at the right layer, and choosing between TCP and UDP.
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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.