The Internet as a Network of Networks · DNS · Web Servers & Clients · Hosting · The Cloud
CSZoneOCR GCSE Computer Science J277
Learning Objectives
By the end of this video you will be able to...
Explain the concept of the Internet as a worldwide collection of computer networks
Explain what DNS is, describe how it is made up of multiple Domain Name Servers, and explain its role in converting a URL to an IP address
Describe the concept of servers providing services and clients requesting services, with examples such as web servers and file servers
Explain what hosting is and how it relates to web servers
Describe The Cloud as remote service provision, and give the advantages and disadvantages of using cloud services
⚡ This is part 3 of 4 covering 1.3.1 — Networks and topologies.
The Internet
A worldwide collection of computer networks
DEFINITION
The Internet is a worldwide collection of computer networks — a vast WAN made up of billions of interconnected devices and countless smaller networks (including LANs and other WANs).
It is not a single network owned by one person or organisation — it is a network of networks, each of which may use different hardware and be managed by different organisations.
The World Wide Web (WWW) is often confused with the Internet — but the Web is a service that runs on top of the Internet, consisting of web pages and websites accessed via a browser. The Internet is the infrastructure that carries it.
⚡ Spec key phrase to use: "a worldwide collection of computer networks." Learn these exact words — they match the specification language.
DNS
Domain Name System — translating names to addresses
DEFINITION
The DNS (Domain Name System) converts a human-readable URL — for example, www.cszone.co.uk — into a numerical IP address that computers use to locate each other on the Internet.
A DNS is made up of multiple Domain Name Servers — servers that hold a database mapping domain names to IP addresses. Because the Internet is so large, no single server holds every address; they work together in a hierarchy to resolve queries.
Humans use easy-to-remember domain names; computers use numeric IP addresses like 192.168.1.1. DNS bridges the gap — without it, we'd need to remember the IP address of every website.
⚡ Spec wording: "A Domain Name Service (DNS) is made up of multiple Domain Name Servers." Know both the system (DNS) and what it's made of (Domain Name Servers, plural).
DNS in Action
URL → IP address: how the lookup works
You type www.cszone.co.uk
→
DNS query sent
→
DNS server looks up IP
→
Returns IP address
→
Browser connects
Step 1: Your device sends a DNS query — it asks a DNS server: "What is the IP address for this domain name?"
Step 2: The DNS server looks up the domain name in its database. If it doesn't know the answer, it asks another DNS server further up the hierarchy.
⚡ Step 3: The IP address is returned to your device, and your browser uses it to connect to the correct web server. This whole process happens in milliseconds, invisibly, every time you visit a website.
Web Servers & Clients
Servers provide services; clients request them
KEY CONCEPT
On the Internet, servers are computers that provide services. Clients are devices that request and use those services. The same principle from client-server networks applies at an Internet-wide scale.
A web server stores and serves web pages. When you visit a website, your browser (the client) sends a request to the web server, which responds by sending back the web page.
A file server provides file storage and retrieval. Other types of server include email servers, print servers, and database servers — each providing a specific service to clients that request it.
⚡ Spec examples to know: web server → web pages; file server → file storage/retrieval. Always link the server type to the specific service it provides.
Hosting
Storing a website so it's accessible on the Internet
DEFINITION
Hosting is the service of storing a website's files on a web server so that they can be accessed by anyone on the Internet.
A web host is a company that provides server space for website files. When you buy hosting, your website is stored on a web server that is permanently connected to the Internet.
When a user visits your website, their browser sends a request to the hosting server, which sends back the web page files. Without hosting, your website would only be accessible on your own device.
⚡ Hosting is essentially renting space on a web server. The web server stays connected to the Internet 24/7, so your site is always available to clients.
The Cloud
Remote service provision over the Internet
DEFINITION
The Cloud refers to services provided remotely over the Internet, rather than on the user's own hardware. These services include storage, software, and processing power.
Cloud storage — files are stored on remote servers and accessed via the Internet (e.g. Google Drive, OneDrive, iCloud).
Cloud software (SaaS) — applications run on remote servers rather than being installed locally (e.g. Google Docs, Microsoft 365 online). Cloud processing — computationally intensive tasks are carried out by remote servers rather than the user's own device.
⚡ The spec defines cloud as "remote service provision (e.g. storage, software, processing)." Know all three types of service.
Cloud — Advantages
Why use the Cloud?
✓
Accessible from anywhere — files and software can be accessed from any device with an Internet connection, not just the one the files were saved on.
✓
No need for local storage — data is stored remotely, so you don't need as much storage space on your own device, and files won't be lost if your device breaks or is stolen.
✓
Easy collaboration — multiple users can access and edit the same files or documents at the same time, from different locations.
✓
Scalable — users can scale storage or processing up or down as needed, often paying only for what they use, without needing to buy or upgrade hardware.
Cloud — Disadvantages
Risks and limitations of the Cloud
✗
Requires Internet access — without an Internet connection, you cannot access cloud services. If the connection is slow or unreliable, performance suffers.
✗
Security and privacy risks — data is stored on servers owned and managed by a third party. If their security is breached, your data could be exposed or stolen.
✗
Ongoing cost — cloud services often require a subscription, meaning you pay continuously rather than making a one-off purchase.
✗
Less control — you are dependent on the cloud provider. If they go down, change their terms, or delete your data, you may lose access to your files or service.
Putting It Together
The Internet, DNS & The Cloud — the big picture
THE INTERNET
Worldwide collection of computer networks. A WAN of WANs and LANs.
DNS
Made of multiple Domain Name Servers. Converts URL → IP address so browsers can find servers.
WEB SERVERS / HOSTING
Web server provides web pages to clients. Hosting = storing a site on a web server so anyone can reach it.
⚡ A common exam question links these concepts: a user visits a website → their browser sends a DNS query → gets an IP address → connects to a web server → which may use cloud hosting.
Exam Practice
Exam-Style Questions — The Internet, DNS & Cloud
Question 1 · 2 marks
Describe the role of a DNS in accessing a website.
2 marks
ANS
A DNS converts a URL (domain name) entered by the user into an IP address. The browser then uses this IP address to connect to the correct web server.
Question 2 · 2 marks
Describe one advantage and one disadvantage of storing files using a cloud service.
2 marks
ANS
Advantage: Files can be accessed from any device with an internet connection, not just the device they were saved on / files are not lost if the device is lost or broken. Disadvantage: Requires an internet connection to access files / data stored on a third party's server may be at risk if their security is breached.
Question 3 · 3 marks
Explain what happens, in terms of DNS and web servers, when a user types a web address into their browser and presses Enter.
3 marks
Common Mistakes
Four mistakes that cost marks in the exam
1
Confusing the Internet with the World Wide Web. The Internet is the global infrastructure of connected networks. The Web is a service that runs on it — a collection of web pages accessed via a browser. They are not the same thing.
2
Describing DNS as "a single server." The spec is explicit: a DNS is made up of multiple Domain Name Servers. If a question asks how DNS works, mention that there are multiple servers working together in a hierarchy.
3
Saying "the Cloud stores data on the Internet." Be precise: the Cloud stores data on remote servers, which are accessed via the Internet. The Internet is the connection method, not the storage location.
4
Only giving one type of cloud service. The spec lists three: storage, software (or SaaS), and processing. If asked to describe cloud services, try to give more than one example type rather than just "cloud storage."
Summary
1.3.1c — The Internet, DNS & The Cloud
THE INTERNET
Worldwide collection of computer networks — a network of networks.
DNS
Multiple Domain Name Servers. Converts URL → IP address for browser to connect.
WEB SERVERS / HOSTING
Web server → web pages. File server → file storage. Hosting = storing a site on a server for Internet access.
THE CLOUD
Remote provision of storage, software and processing. Advantages and disadvantages apply.
⚡ Exam tip: know the exact spec phrases — "worldwide collection of computer networks," "multiple Domain Name Servers," "remote service provision."
CSZone.co.uk
That's 1.3.1c done.
Next up: 1.3.1d — Star & Mesh Network Topologies
Full quiz, marked worksheet and slides at CSZone.co.uk