Computer Networks and the Effects of Using Them

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Introduction to Computer Networks

A computer network is a collection of two or more computers, along with other devices such as printers and servers, that are connected together so they can share data, hardware, and software resources. Networks range in size from a small home network connecting a few devices, to a school or business Local Area Network (LAN), to the internet itself, which links millions of networks worldwide. Understanding how networks are structured and the effects they have on individuals and society is a key part of the Cambridge IGCSE ICT syllabus.

Local Area Networks (LANs) and Wide Area Networks (WANs)

A Local Area Network (LAN) connects computers and devices within a single building or a small group of nearby buildings, such as a school campus or an office. LANs are usually owned and maintained by a single organisation and can be connected using either cables (a wired LAN) or radio signals (a wireless LAN, or WLAN). A Wide Area Network (WAN) connects computers over a much larger geographical area, such as between cities or countries, and typically relies on telecommunications infrastructure provided by an external company, since no single organisation could realistically lay its own cables across such distances. The internet is the largest example of a WAN, connecting countless smaller networks around the world.

Network Hardware

Several pieces of hardware are needed to build and operate a network. A router directs data between different networks and is commonly used to connect a home or school network to the internet. A switch connects multiple devices within the same LAN and directs data only to the specific device it is intended for, rather than to every device on the network, making the network more efficient than older technology. A Network Interface Card (NIC) allows an individual computer to connect to a network, and wireless access points allow devices to join a network without a physical cable by using radio signals.

The Internet, Intranets, and Extranets

The internet is a vast, publicly accessible global network of networks that anyone can connect to, typically through an Internet Service Provider (ISP). An intranet is a private network, based on the same technology as the internet, but restricted to the employees or members of a single organisation, and is often used to share internal documents, news, and resources securely. An extranet is similar to an intranet but is extended to allow limited, controlled access to selected external users, such as suppliers or business partners, who need to view specific information without gaining access to the whole internal network.

Data Transmission and Bandwidth

Data travels across a network as a stream of digital signals, and the maximum amount of data that a network connection can carry in a given time is known as its bandwidth, usually measured in bits per second. A connection with high bandwidth can transfer large files, such as videos, more quickly than a connection with low bandwidth, which is why bandwidth is an important factor when a school or business chooses an internet service.

The Effects of Using IT on Employment

The widespread use of networks and ICT more generally has had significant effects on the way people work. Some traditional jobs, such as manual data entry and routine assembly line work, have been reduced or eliminated as computers and robots have taken over repetitive tasks. At the same time, entirely new types of jobs have been created, including network technicians, cyber security specialists, app developers, and social media managers, roles that did not exist before networked computing became widespread.

The Effects of Using IT on Working Patterns

Networking technology, and particularly the internet, has enabled new working patterns such as teleworking, where employees work from home or another remote location and connect to their organisation's network over the internet. This can reduce commuting time and costs for employees and reduce office space costs for employers, but it can also lead to feelings of isolation, blur the boundary between work and home life, and require strong self-discipline to remain productive without direct supervision.

The Effects of Using IT on Communication and Society

Networks have transformed how people communicate, allowing instant messaging, video calls, and email to replace much slower forms of communication such as letters. Social networking sites allow people to stay in touch with friends and family across the world, but concerns have also been raised about cyberbullying, the spread of false information, and the amount of personal data that such sites collect about their users. Networks have also enabled online banking, online shopping, and e-government services, making many everyday tasks more convenient but also raising the risk of fraud and identity theft if security is not properly managed.

Network Security Considerations

Because networked computers can be accessed remotely, security is a major concern. Firewalls are used to monitor and control incoming and outgoing network traffic based on security rules, helping to block unauthorised access. Encryption scrambles data so that it cannot be understood if it is intercepted while travelling across a network, and user authentication methods, such as usernames, passwords, and two-factor authentication, help ensure that only authorised people can access network resources.

Network Topologies

The physical or logical arrangement of devices on a network is known as its topology. In a star topology, every device is connected individually to a central switch or hub, so that if one cable fails only that one device loses its connection while the rest of the network keeps working, making this the most common topology used in schools and offices today. In a bus topology, all devices share a single central cable, which is cheaper to install but means the whole network can be disrupted if the main cable is damaged. A mesh topology, where many devices are interconnected with multiple paths between them, is more resilient still and is often used for wireless networks and the backbone of the internet itself.

Wired Versus Wireless Networking

Wired networks use physical cables, such as twisted pair or fibre optic cable, to connect devices, and generally offer faster, more stable, and more secure connections because signals are not affected by interference from walls or other wireless devices. Wireless networks use radio waves, most commonly through Wi-Fi, to connect devices without cables, offering greater flexibility and mobility since users can connect from anywhere within range, though wireless signals can be slower, less reliable, and more vulnerable to interception if not properly secured with strong encryption.

Key Terms to Remember

• LAN (Local Area Network): a network covering a small geographical area, such as one building.
• WAN (Wide Area Network): a network covering a large geographical area, such as between cities or countries.
• Bandwidth: the maximum amount of data a network connection can carry in a given time.
• Firewall: hardware or software that monitors and controls network traffic to block unauthorised access.

Summary

Computer networks allow devices to share data, hardware, and software, and range from small LANs to the vast, global WAN that is the internet. Networking hardware such as routers and switches makes this sharing possible, while intranets and extranets extend network principles to serve the specific needs of organisations. The growth of networking has profoundly affected employment, working patterns, and communication in society, bringing both significant benefits and new risks that must be managed through effective network security.