A Professor Wingman Class 404
NetMgmt.Lab

Week 4

Networking Fundamentals and the OSI Model

Learn the building blocks of networking and the seven OSI layers used to troubleshoot communication problems.

Lesson recap

The OSI model is the shared vocabulary every networking professional uses to describe where a problem lives. When a user says 'the internet is broken,' a tech mentally walks the layers: Is the cable plugged in (Layer 1)? Does the switch see the MAC (Layer 2)? Did DHCP give the PC an IP (Layer 3)? Is the firewall blocking the port (Layer 4)? Is the browser misconfigured (Layer 7)? You don't need to memorize every protocol — you need to know which layer to look at first. The pizza mnemonic ('Please Do Not Throw Sausage Pizza Away') will live in your head for the rest of your career.

Learning goals

  • Explain what a network does
  • Describe LANs and WANs
  • Identify common network devices
  • Explain IP address, default gateway, and DNS basics
  • Identify the seven OSI layers
  • Use the phrase "Please Do Not Throw Sausage Pizza Away" to remember the layers
  • Match common problems to OSI layers

Key terms

Network

Connected devices that communicate or share resources.

LAN

Local Area Network — devices in one building or office.

WAN

Wide Area Network — networks spanning cities or countries (the internet is the biggest WAN).

Router

Connects different networks; decides where packets go.

Switch

Connects devices inside the same LAN; forwards frames by MAC address.

Access Point (AP)

Lets wireless devices join a wired LAN.

OSI Model

A seven-layer reference model for network communication.

Encapsulation

Wrapping data with headers as it moves down the OSI stack.

Curated videos

OSI Model Explained

TechTerms / PowerCert

Computer Networking Course (Network+ prep)

freeCodeCamp.org

Checkpoint checklist

Sign in to save your progress across devices.
  • Build the OSI memory table
  • Match problems to OSI layers
  • Draw a basic network diagram
  • Practice network vocabulary
  • Complete an OSI troubleshooting scenario
  • Create OSI Model study sheet
  • Saved required evidence
  • Answered the reflection questions

Pro tips from the instructor

  • ★Troubleshoot bottom-up: cable → link lights → IP → gateway → DNS → application. Most outages die at Layer 1 or 3.
  • ★Layer 2 talks in MAC addresses, Layer 3 talks in IPs. ARP is the bridge between them.
  • ★If exactly one website is broken but others work, you're at Layer 7 (application/DNS) — not the network.

Try this — stretch exercises

Optional hands-on practice that goes beyond the workbook. Check items off as you complete them — progress saves in this browser.

0/2
  • For three real outages you've personally seen (Wi-Fi dropped, video froze, page won't load), assign each to an OSI layer and defend your answer.
  • Sketch your home network — every device, every cable, every wireless link — on a single page.

Files to save this week

  • 📁 Week04_OSITable_YourLastName.png
  • 📁 Week04_NetworkDiagram_YourLastName.png
  • 📁 Week04_OSITroubleshooting_YourLastName