In simple terms
A friendly intro before the formal notes — no formulas yet.
From Your Click to the Cosmos
The internet is not a cloud; it's a physical system of connected computers and cables governed by a set of rules. These rules ensure that your request for a website finds its way to the right server and the data comes back to you, no matter where in the world it is.
Think of the internet like a global postal service. Your computer is your house, and you want to send a letter (a data request) to a friend's house (a web server). You don't know their exact physical coordinates, just their home address (e.g., 'www.example.com'). The postal service uses a giant address book (DNS) to find the coordinates (IP address), breaks your long letter into small, numbered postcards (packets), and sends them via a network of roads and sorting offices (routers and switches). The postcards are reassembled in the correct order at the destination (TCP).
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First, identify the core components. Your device (a client) connects via hardware like switches and routers to a local network.
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Next, understand the network's scale. Your Local Area Network (LAN) connects to a vast Wide Area Network (WAN) – the internet itself.
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Then, translate the address. The Domain Name System (DNS) acts like a phonebook, converting human-friendly web addresses into machine-readable IP addresses.
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Finally, deliver the data. The TCP/IP protocol suite breaks your data into packets, routes them across the network, and ensures they are all received and reassembled correctly.
Explore the concept
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Key formulas
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Full topic notes
Formal explanation with the rigour you need for the exam.
The Core Components: Hardware and Architecture
At its heart, any network consists of nodes (devices like computers, printers) and connections (wired or wireless). Specialised hardware manages the flow of traffic. A server is a powerful computer that provides data or services to other computers, known as clients. A switch creates a network by connecting devices within a single LAN, while a router connects different networks together, forming the backbone of the internet.
Client: A device that requests information (e.g., your laptop's browser).
Server: A device that stores and provides information (e.g., the computer hosting a website).
Switch: Connects devices on one local network (LAN) using MAC addresses.
Router: Connects different networks (e.g., your home LAN to the internet) using IP addresses.
The Rules of Communication: Internet Protocols
For billions of devices to communicate seamlessly, they must all follow a standard set of rules, or protocols. The foundational suite for the internet is TCP/IP. Think of it as two partners: IP is responsible for addressing and routing packets of data to the correct destination, like a postman using an address. TCP is responsible for ensuring all the packets arrive reliably and are reassembled in the correct order, like someone checking the contents of the delivery against a list.
The TCP/IP Model (Conceptual Layers):
- Application Layer (e.g., HTTP, FTP, SMTP) - Where user applications interact with the network.
- Transport Layer (e.g., TCP, UDP) - Manages session and connection, ensuring reliable data transfer.
- Internet Layer (e.g., IP) - Handles addressing and routing of packets across networks.
- Link Layer (e.g., Ethernet, Wi-Fi) - Manages the physical transmission of data.
Another crucial protocol is the Domain Name System (DNS). Humans remember names like www.ibo.org, but computers communicate with IP addresses (e.g., 104.18.33.121). DNS acts as the internet's translator, converting the domain names you type into the IP addresses required for routing.
For high marks, avoid simply defining terms. Instead, explain their function in relation to each other. For example, don't just say 'DNS translates names'. Explain that a browser first sends a DNS query to a DNS server to resolve a domain name into an IP address, and then uses that IP address to establish a TCP connection with the target web server. This shows a deeper understanding of the process.
Worked examples
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A new secondary school is designing its campus network. The IT department is debating between a fully wired Ethernet LAN and a comprehensive Wi-Fi (WLAN) solution for all classrooms and offices. Evaluate these two options, considering cost, performance, security, and mobility. Justify which solution, or combination of solutions, you would recommend.
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A comprehensive evaluation requires balancing competing factors.
A student in London types https://www.example.com into their web browser and presses Enter. The web server for example.com is located in California. Outline the key steps involved in resolving the name and retrieving the webpage, mentioning at least four different technical components or protocols.
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DNS Lookup: The student's browser first needs to find the IP address for www.example.com. It sends a query to a local DNS resolver (likely provided by their Internet Service Provider, ISP). This resolver may query a root DNS server, then a TLD (.com) server, and finally the authoritative name server for example.com to get the corresponding IP address (e.g., 93.184.216.34). [1 mark for explaining DNS role]
How it all connects
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Glossary
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Quick check
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Revision flashcards
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What is a LAN (Local Area Network)?
A network that connects computers and devices in a limited geographical area such as a home, school, or office building. Typically owned and managed by a single person or organisation.
Key takeaways
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Client: A device that requests information (e.g., your laptop's browser).
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Server: A device that stores and provides information (e.g., the computer hosting a website).
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Switch: Connects devices on one local network (LAN) using MAC addresses.
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Router: Connects different networks (e.g., your home LAN to the internet) using IP addresses.
Practice — then mark it
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Test your knowledge on Computers, Networks and the Internet
Test your knowledge on Computers, Networks and the Internet
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