Year 7 · Autumn 2
Networks · Lesson 3 of 5
LANs and WANs: routers, switches and cables
TheoryTopic 15 Networks and the internet
Year 7 · Networks · Lesson 3 of 5
You will learn to
- Explain the difference between a LAN and a WAN, with an example of each.
- Identify the job of a switch, a router and a wireless access point.
- Draw the school network from this room out to the internet.
Year 7 · Networks · Lesson 3 of 5
Success criteria
You have got it when you can say:
- I can label a switch, router, server, cable and Wi-Fi on my drawing.
- I can say whether the school network is a LAN or a WAN, and why.
- I can explain that the internet is the biggest WAN.
Year 7 · Networks · Lesson 3 of 5
Retrieval starter
Questions from before. Write your answers, then show them.
- Last lesson
Why do computers use 2 states instead of 10?
A On and off are easy to tell apart reliablyB Two is the biggest numberC Ten states would be too cheap
A. On and off are easy to tell apart reliably
- Last unit
Spreading ransomware that locks a company's files is which CMA offence?
A Section 2B Section 1C Section 3
C. Section 3
- Earlier this unit
A 400 MB file on a 100 Mbps line takes at best…
A 4 secondsB 32 secondsC 40 seconds
B. 32 seconds
Year 7 · Networks · Lesson 3 of 5
Key words (1 of 3)
- LAN
- Local Area Network: a network over a small area.
- LAN / WAN
- Local Area Network: a network over a small area.
- Router
- Connects different networks and forwards packets.
- IP address
- A device's address on a network. IPv4 = 4 bytes.
Year 7 · Networks · Lesson 3 of 5
Key words (2 of 3)
- MAC address
- Fixed unique ID of a network card. 48 bits in hex.
- DNS
- Domain Name System: turns website names into IP addresses.
- Packet
- A small numbered chunk of data sent across a network.
- Protocol
- A set of agreed rules for communication.
Year 7 · Networks · Lesson 3 of 5
Key words (3 of 3)
- Bandwidth / latency
- How much data a connection can carry per second.
The explanation · step 1 of 1
LAN and WAN
| LAN | WAN | |
|---|---|---|
| Covers | A home, school or office | Cities, countries, the world |
| Owned by | Usually whoever uses it | Often rented from telecoms companies |
| Example | The school network | The internet is the biggest WAN |
Year 7 · Networks · Lesson 3 of 5
Quick quiz · 1 of 3
Packets arrive out of order. How are they fixed?
- A The router sorts them
- B Sequence numbers
- C They're sent again
B. Sequence numbers
The receiver puts them back in order by number.
Year 7 · Networks · Lesson 3 of 5
Quick quiz · 2 of 3
Which device joins your home LAN to your ISP's network?
- A Wireless access point
- B Router
- C Switch
B. Router
A router joins different networks. A switch only joins devices inside one LAN.
Year 7 · Networks · Lesson 3 of 5
Quick quiz · 3 of 3
In a star network the central switch breaks. What happens?
- A Every device loses the network
- B Data finds another route
- C Only one device drops off
A. Every device loses the network
The switch is a single point of failure: everything goes through it.
Year 7 · Networks · Lesson 3 of 5
Exit ticket
Answer on paper before you go. Then check.
Which protocol checks every packet arrived and asks again for missing ones?
A TCPB FTPC IP
A. TCP TCP (transport layer) numbers packets and resends lost ones. IP just addresses and routes them.
A game feels laggy, but big downloads are fast. The problem is most likely…
A Too many IP addressesB High latencyC Low bandwidth
B. High latency Game moves are tiny, so the waiting time (latency) matters, not the lanes (bandwidth).