Purpose and characteristics of networks
Describe the purpose and characteristics of networks
In this lesson
- Why computers are connected in networks
- The characteristics of local area networks (LAN), wide area networks (WAN) and personal area networks (PAN)
- How a virtual private network (VPN) extends a private network securely across a public one
LearnWhy networks exist
A network is two or more devices connected so that they can exchange data, by cable or wirelessly.
LearnLAN, WAN and PAN
| PAN — personal area network | LAN — local area network | WAN — wide area network | |
|---|---|---|---|
| Scope | One person's devices, within about 10 metres | One site: a home, school, office or hospital, up to about 1 km | Cities, countries and continents; often connects many LANs |
| Typical connections | Bluetooth, USB, Wi-Fi Direct | Ethernet cables and Wi-Fi | Fibre-optic and leased lines, satellite links, the public internet |
| Ownership | The user | The organisation or household that uses it | Usually links rented from telecommunications companies; the internet is the largest WAN |
| Speed and latency | Usually low power and short range; data rates vary with the technology | High bandwidth, low latency | Lower bandwidth per user and higher latency, because of the distances and many links |
| Purpose | Connect personal devices to each other | Share resources and communicate within one site | Connect sites and users that are far apart |
| Example | A smartwatch sending fitness data to a phone | Computers, printers and servers in a school | A bank connecting its branches to its head office |
A metropolitan area network (MAN), covering one city, sits between a LAN and a WAN.
CheckWhich type of network?
Classify each network.
- Wireless earbuds connected to a phone
- The Wi-Fi and cabled network in a hospital
- A supermarket chain linking the tills in 400 stores to its head office
- A laptop using a wireless keyboard and mouse
- Computers and printers on two floors of an office
- The internet
LearnVirtual private networks
LabInside the tunnel
An employee in a café needs the company's payroll system. Switch the VPN on and off, and compare what an eavesdropper on the café Wi-Fi sees with what the company's VPN gateway sees.
- Laptop in café
- Café Wi-Fi
- Public internet
- Company VPN gatewaycompany network closed to the internet
- Payroll servernot reachable
Without a VPN
The payroll server is on the company’s private LAN. The company firewall does not let connections from the internet reach it, so the employee cannot use it from the café at all.
Anything the laptop sends to ordinary websites without encryption (plain HTTP) can be read by anyone monitoring the café Wi-Fi:
Look at the data without a VPN, then with a VPN from both points of view, to complete this activity.
CheckQuick check
Which statement about a VPN is correct?
ExamWorked exam answer
Outline one limitation of using a VPN.
[2]ReviewMistakes examiners see
Size alone is not enough. Describe networks by scope and purpose, ownership and typical speed.
A VPN is not a physical network. It runs on top of the public internet.
The internet and the World Wide Web are not the same. The internet is the network; the web is one service that runs on it.
For VPN answers, use the words encryption, tunnel, public network and authentication.
Exam practiceExam-style questions
5 questions · 11 marks. Answer each one first, then mark it yourself against the markscheme. Your answers are saved in this browser only.
An international school has a network in its main building. Teachers sometimes mark work from home, and the school is opening a second campus in another city.
State the type of network that connects the computers and printers in the school's main building.
Outline one purpose of connecting the school's computers in a network.
Describe the characteristics of the network that will connect the two campuses.
Explain how a VPN allows teachers to access the school's file server securely from home.
Identify two characteristics of a personal area network (PAN).
0 of 5 questions marked. Mark every question to see your total.
Exam-style questions written for Praxis IB in the format of the 2027 specimen papers. They are not IB past-paper questions.