Start with the recap, study the fully worked examples, then use the practice problems to
check your understanding of Network.
This page combines explanation, solved examples, and follow-up practice so you can move
from recognition to confident problem-solving in CS Thinking.
Concept Recap
A group of interconnected computing devices that can communicate and share resources with each other. Networks range from small local area networks (LANs) connecting devices in one building to wide area networks (WANs) spanning cities or countries, up to the global internet.
A network is like a postal system for computers — it connects them so they can send and receive information.
Read the first worked example with the solution open so the structure is clear.
Try the practice problems before revealing each solution.
Use the related concepts and background knowledge badges if you feel stuck.
What to Focus On
Core idea:Networks enable communication and resource sharing. They range from local (LAN) to global (internet).
Common stuck point:The internet is a network of networks, not a single thing. No one entity owns or controls it all.
Sense of Study hint:When learning about networks, start with the simplest case: two computers connected by a cable. Then scale up: a LAN connects devices in one location, a WAN connects locations across a city or country, and the internet connects networks globally. Focus on how devices find each other (addresses) and how data travels (packets).
Worked Examples
Example 1
easy
What is a computer network? Describe two benefits of connecting computers in a school network.
Answer
A network connects computers to share resources. Benefits: shared printers/storage, easy communication and file sharing.
First step
1
Step 1: A computer network is two or more computers connected together to share data and resources.
Full solution
2
Step 2: Benefit 1: Resource sharing — all computers can use shared printers, storage, and internet connection instead of each needing their own.
3
Step 3: Benefit 2: Communication — students and teachers can share files, send messages, and collaborate on documents across the network.
Networks are fundamental to modern computing. From small office networks to the global internet, connecting computers multiplies their usefulness far beyond what standalone machines can offer.
Example 2
medium
Explain the difference between a LAN and a WAN. Give an example of each.
Example 3
medium
A small office wants reliable sharing among 8 devices and tight budget. Recommend a topology and explain why.
Example 4
hard
Compare ring vs star for a small office of 6 devices where one device often goes offline. Which topology is more tolerant?
Example 5
challenge
Design a network for a 200-device school: 10 classrooms, library, and admin office, with internet uplink. Sketch topology and classify.
Practice Problems
Try these problems on your own first, then open the solution to compare your method.
Example 1
medium
Describe two network topologies (star and mesh) and give one advantage and one disadvantage of each.
Example 2
hard
Explain the client-server and peer-to-peer network models. For a school, which model is more appropriate for (a) file storage and (b) video calling between two students?
Example 3
easy
What does LAN stand for?
Example 4
easy
What does WAN stand for?
Example 5
easy
Do networks require physical cables? Yes or no.
Example 6
easy
In a star topology, all devices connect to one central point. What is that central device usually called?Star topology — all devices connect to one central hub (or switch)
Example 7
easy
Is Wi-Fi the same thing as having internet access? Yes or no.
Example 8
easy
A topology where every device connects to every other directly is called what?Mesh topology — every device connects directly to every other device
Example 9
easy
What is the main purpose of a network in one phrase?
Example 10
easy
Connecting two LANs in two different cities forms which kind of network?
Example 11
medium
In a ring topology, data passes device to device in a loop. If one link breaks, what can happen to communication?
Example 12
medium
Which topology best tolerates a single cable failure: bus, star (one hub), or mesh?Mesh topology — 4 nodes, 6 links; multiple paths survive a single cable failure
Example 13
medium
A home network: laptop, phone, and printer all connect to one router. Name the topology.Home star topology — laptop, phone, and printer all connect to one router
Example 14
medium
Five offices each connect only to a shared central office. Total point-to-point links?5 offices → central hub: a star with exactly 5 links
Example 15
medium
In a full mesh of 4 devices, how many direct links exist? (each pair connected once)Full mesh of 4 devices — C(4,2) = 6 direct links
Example 16
medium
You are on Wi-Fi but cannot load any website. The Wi-Fi icon shows connected. Is the LAN link or the internet uplink more likely down?
Example 17
medium
Classify by scope: (a) office building network, (b) city-wide university campuses linked. Which is the LAN?
Example 18
medium
A full mesh of 5 devices: how many direct links? (each pair once)Full mesh of 5 devices — C(5,2) = 10 direct links
Example 19
medium
Classify by scope: a network spanning several cities in one region. LAN or WAN?
Example 20
challenge
Why does adding devices to a full-mesh network become impractical quickly? Use the link count for n devices.
Example 21
challenge
Compare a single-hub star and a full mesh on this trade-off: which is cheaper to wire, and which survives a central failure?Star: 6 devices, 6 links — cheap but hub is a single point of failure
Example 22
challenge
A network connects 3 buildings on a campus and also links out to the public internet. Classify the on-campus part and the external link.
Example 23
easy
True or false: the World Wide Web and the internet are the same thing.
Example 24
easy
A coffee shop Wi-Fi works but no web page loads. Which is more likely working: the LAN or the WAN uplink?
Example 25
easy
In a bus topology, all devices share one ____.
Example 26
easy
Name one wireless way to form a network without cables.
Example 27
easy
A school computer room of 25 PCs connected to one switch is best classified as a what?
Example 28
medium
A full mesh of 6 devices has how many direct links (each pair once)?Full mesh of 6 devices — C(6,2) = 15 direct links
Example 29
medium
In a single-hub star with 10 devices plus the hub, how many cables to the hub?Star with 10 devices — exactly 10 cables connect to the central hub
Example 30
medium
A network connects 4 cities, each with multiple LANs, via leased lines. LAN or WAN overall?
Example 31
medium
Which device usually sits at the center of a home star network?
Example 32
medium
A campus has 3 buildings linked by fiber, each building has its own LAN. What type of network is the campus-wide collection?
Example 33
medium
For a client-server model, which side typically stores files centrally: client or server?Client-server model — clients request files from the central server
Example 34
medium
A full mesh of 10 devices: how many direct links?
Example 35
medium
Two students on the same Wi-Fi want to play a 2-player game over the LAN. Client-server or peer-to-peer is simpler to set up?
Example 36
medium
In a star topology, if the hub fails, how many devices can still communicate via the hub?Star with failed hub — 0 devices can communicate via the hub
Example 37
medium
A satellite link from a remote village to the rest of the world makes the village part of which scope of network?
Example 38
hard
You have 12 devices in a partial mesh where each device connects to 3 others. How many undirected links?
Example 39
hard
A full mesh of n devices uses n(n−1)/2 links. For n=20, how many links, and how many does the star use?
Example 40
hard
Why is the internet best modeled as a network-of-networks rather than one giant LAN?
Example 41
hard
In a hybrid topology, a campus core uses a mesh among 4 routers, and each router connects 25 devices in a star. Total core mesh links?Hybrid topology — mesh core (4 routers, 6 links) + star edges for hosts
Example 42
hard
A video call between two students directly (peer-to-peer) typically has lower latency than via a central server. Why?
Example 43
challenge
For what n does a full undirected mesh first exceed 100 links?