Computer networks are everywhere – in homes, schools, businesses, and across the world through the internet. Understanding how these networks are built, connected, and maintained is a core part of modern computer science. This worksheet introduces the foundational knowledge needed to explore computer networks. It covers the difference between LANs and WANs, how network hardware works, how devices are physically arranged using topologies, and how users access content across the internet. By learning these concepts, students can better understand how devices communicate, how data travels from one point to another, and how to evaluate the effectiveness of different network designs.
This worksheet also links each key topic to a relevant Craig 'n' Dave video that breaks down the concepts visually and clearly. Students should read each explanation carefully, watch the corresponding video, then complete the follow-up questions to check their understanding.
Terminology:
LAN – Local Area Network
WAN – Wide Area Network
Bandwidth – The amount of data that can be transferred per second
NIC – Network Interface Controller
Switch – Device that directs data to the correct destination on a network
Router – Connects different networks together
WAP – Wireless Access Point
Star Topology – All devices connect to a central switch
Mesh Topology – All devices connect directly to multiple other devices
DNS – Domain Name System
Hosting – Providing web content and services to users
A Local Area Network (LAN) connects computers and devices in a small geographical area such as a school, office, or home. LANs are usually privately owned and maintained. They are fast, secure, and cheap to run over short distances. In contrast, a Wide Area Network (WAN) covers a much larger area, often across cities or countries. WANs use public or leased infrastructure like telephone lines or satellites and are typically used by governments, corporations, and the Internet.
For example, a school's network connecting its computer labs is a LAN. The school's connection to an external education platform hosted elsewhere uses a WAN.
Key Facts:
LANs are local, fast, and privately managed.
WANs are large-scale and use external infrastructure.
LANs are cheaper and more secure for internal use.
This video explains the key differences between LANs and WANs, including examples of when each is used.
Questions:
What is a LAN, and where might you find one?
What is a WAN, and how is it different from a LAN?
Why might a business prefer a LAN for its office?
Network performance refers to how efficiently a network transmits data. Factors that affect performance include bandwidth (how much data can move at once), the number of users (too many people can slow it down), and the type and quality of hardware in use. For example, a network with high-speed fibre optic cables will perform better than one using older copper wiring.
A school might experience slower internet during lunch when everyone is streaming videos on their phones—this is due to limited bandwidth and high user demand.
Key Facts:
Bandwidth affects how much data moves at once.
Network performance drops if too many users share limited resources.
Good quality hardware can improve network speed and reliability.
This video looks at what affects network speed and reliability, including bandwidth and number of users.
Questions:
What is bandwidth?
What happens when many users are on a network?
How can hardware affect performance?
Networks are made up of various hardware components. A Network Interface Controller (NIC) allows a device to join a network. A switch sends data to specific devices in a LAN, while a router connects the LAN to external networks like the internet. A Wireless Access Point (WAP) allows wireless devices to connect to the network.
For example, in a home setup, your router acts as both router and WAP, and each device uses a NIC (often built-in) to connect.
Key Facts:
NICs connect devices to networks.
Switches manage traffic within LANs.
Routers connect different networks.
WAPs provide wireless access.
This video introduces the key hardware used in LANs like routers, switches, WAPs, and NICs.
Questions:
What does a NIC do?
What is the role of a switch?
What is the purpose of a router?
A network topology is the layout of devices in a network. In a star topology, each device connects to a central switch. This layout is simple and easy to manage, but if the switch fails, the whole network goes down. In a mesh topology, devices are connected to many others. It’s more expensive but much more reliable—if one link fails, data can take another route.
For example, schools often use star topologies for ease and cost, while emergency systems may use mesh for reliability.
Key Facts:
Star topology is cheap and easy to manage.
Mesh topology is fault-tolerant and robust.
Mesh costs more but avoids a single point of failure.
This video explains the difference between star and mesh topologies and when each is best used.
Questions:
What is a star topology?
Why is mesh more fault-tolerant?
When might a mesh topology be used?
The Internet is a global system of interconnected networks (a WAN). The World Wide Web is a service that operates on the internet, allowing users to access websites. The Domain Name System (DNS) translates human-readable website names like google.com into machine-readable IP addresses. Hosting means storing a website’s files on a server so other users can access them.
For example, when you enter www.bbc.co.uk into your browser, DNS finds the correct server IP, and hosting makes the website content available.
Key Facts:
The internet connects networks worldwide.
DNS links web addresses to IP addresses.
Hosting stores website files so users can access them.
This video explores how the Internet works and how DNS translates website names to IP addresses.
Questions:
What is the Internet?
What is DNS?
Why is hosting needed?
There are two main types of network models: client-server and peer-to-peer. In client-server networks, one or more servers manage resources, users, and data. Clients request services from these servers. This is ideal for schools, offices, and large organisations. In peer-to-peer (P2P) networks, all devices can act as both client and server—sharing resources directly. These are easier to set up but harder to manage and secure.
For example, a school with hundreds of users will use client-server. Two friends sharing files at home might use P2P.
Key Facts:
Client-server uses centralised control.
Peer-to-peer shares resources without central servers.
Client-server is better for security, backups, and updates.
This video explains the difference between client-server and peer-to-peer networks using practical examples.
Questions:
What is a client-server network?
What is a peer-to-peer network?
Which would work better in a school and why?