In simple terms
A friendly intro before the formal notes — no formulas yet.
How Computers Talk
A computer network is simply a group of computers connected together to share resources and communicate. This process is governed by a set of rules, much like grammar in a language, ensuring messages are sent and received correctly.
Imagine sending a large encyclopedia through the post. You wouldn't send it as one giant, unwieldy book. Instead, you'd split it into individual pages (packets), put each page in a separate envelope with the destination address, and mail them. The postal service (network routers) would deliver them, possibly out of order, and the recipient would reassemble them into the original encyclopedia. Protocols are the postal rules everyone agrees on, like how to write an address and what size an envelope can be.
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A large piece of data, like an email or a photo, is prepared for sending.
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The data is broken down into smaller, manageable chunks called packets. Each packet is labelled with the sender's and receiver's address (IP address) and a sequence number.
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Network devices like routers examine the address on each packet and forward it along the best path towards its destination.
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At the destination computer, the packets are received, checked for errors, and reassembled in the correct order to recreate the original data.
Explore the concept
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Full topic notes
Formal explanation with the rigour you need for the exam.
Fundamentals of a Network
At its simplest, a computer network consists of two or more computers connected together. The primary purpose of a network is to facilitate the sharing of resources and information. These resources can be hardware (like a printer), software (like a shared application), or data (like files in a shared drive).
Advantages: Resource sharing (printers, files), enhanced communication (email, messaging), cost reduction (sharing expensive peripherals), centralised administration.
Disadvantages: Security risks (unauthorised access, malware), management complexity, initial setup cost, potential for widespread failure if a central component fails.
Network Types: LAN vs. WAN
Networks are often classified by their geographical scope. The two most common types you need to know are Local Area Networks (LANs) and Wide Area Networks (WANs). A LAN is confined to a small area, like a single building, and is typically owned and managed by a single organisation. A WAN connects networks over a large geographical area, often using infrastructure from telecommunication companies. The Internet is the ultimate example of a WAN.
Protocols: The Rules of Communication
For devices on a network to communicate, they must agree on a set of rules, or protocols. These protocols define the format, order, and meaning of messages sent and received. Without protocols, data sent from one machine might be unintelligible to another. The most dominant protocol suite is TCP/IP (Transmission Control Protocol/Internet Protocol), which forms the basis of the Internet.
HTTP (HyperText Transfer Protocol): The foundation of data communication for the World Wide Web.
HTTPS (HTTP Secure): A secure version of HTTP where communications are encrypted.
FTP (File Transfer Protocol): Used to transfer computer files between a client and server on a network.
TCP (Transmission Control Protocol): Provides reliable, ordered, and error-checked delivery of a stream of packets. It's connection-oriented.
IP (Internet Protocol): Responsible for addressing hosts and routing packets from a source to a destination across one or more networks.
For your exam, don't just memorise the acronyms. You must be able to explain the function of key protocols. For example, state that TCP ensures data arrives correctly and in order, while IP is responsible for getting the data to the right address.
Data Transmission and Performance
Data is sent across most modern networks using a technique called packet switching. Large files are broken into small blocks called packets. Each packet contains a portion of the data, plus a header with control information like the source and destination IP addresses and a sequence number. These packets are sent independently across the network and reassembled at the destination. This is efficient as it allows many users to share the same network infrastructure.
Worked examples
See the formulas applied — reveal one step at a time, like the exam.
A new graphic design studio with 15 employees is setting up in a single office floor. They need to share large design files and a high-quality colour printer. Justify, with two distinct reasons, whether a LAN or a WAN would be more appropriate for this setup.
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A LAN (Local Area Network) would be the appropriate choice. [1]
A 10 MB photograph is transmitted over a network. The data is divided into packets, where each packet has a maximum payload size of 1500 Bytes and a header of 40 Bytes is added to each packet. Calculate the total amount of data transmitted in Bytes. (Assume 1 MB = Bytes).
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Convert file size to Bytes:
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 computer network?
A collection of interconnected computing devices that can exchange data and share resources.
Key takeaways
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Advantages: Resource sharing (printers, files), enhanced communication (email, messaging), cost reduction (sharing expensive peripherals), centralised administration.
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Disadvantages: Security risks (unauthorised access, malware), management complexity, initial setup cost, potential for widespread failure if a central component fails.
Practice — then mark it
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Test Your Knowledge on Network Fundamentals
Test Your Knowledge on Network Fundamentals
Extra simulations & links
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Frequently asked
Checkpoint
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