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IB DP Computer Science Study Notes

1.2.1 Computer System Components

In the rapidly advancing field of information technology, understanding the fundamentals of computer system components and their interplay within networked environments is crucial. This understanding helps in appreciating how individual pieces of technology come together to form complex, interconnected systems. Furthermore, it's essential to consider the social and ethical implications these technologies bring to our global society.

Defining Key Terms


  • Hardware refers to the tangible, physical elements of a computer system.
  • Major components include the CPU (the 'brain' of the computer), RAM (short-term memory), storage devices (like HDDs and SSDs for long-term data storage), and motherboards (which connect all internal components).
  • External hardware, like monitors, keyboards, and printers, are known as peripherals.


  • Software is the collection of data, programs, and instructions used to direct hardware to perform desired tasks.
  • Operating Systems (OS) like Windows, macOS, and Linux manage the hardware and create an environment for other software to run.
  • Application software, like Microsoft Office or Adobe Photoshop, enables users to perform specific tasks.


  • Peripherals extend a computer's capabilities, connecting externally or internally, and can be input, output, or storage devices.
  • Input devices (e.g., keyboard, mouse) allow users to input data, whereas output devices (e.g., monitors, printers) display or project data.
  • Some peripherals, like external hard drives, serve for both storage and data transfer functions.


  • A network in computing refers to a collection of interconnected computers and devices that can share resources and data.
  • Networks can range from small local area networks (LANs) in a single building to massive, spread-out wide area networks (WANs), like the Internet.
  • Components of a network include routers, switches, cables, and wireless access points.

Human Resources

  • Human Resources in IT encompass all personnel involved in system analysis, design, implementation, maintenance, and management.
  • They play key roles in project management, technical support, security, and ensuring that IT infrastructure aligns with organisational goals.

Roles of Computers in a Networked World


  • In networking, a client is a device that accesses shared network services provided by another computer (server).
  • Clients can be a variety of devices like desktop computers, laptops, smartphones, etc.


  • Servers are powerful computers or software systems that provide data, services, or resources to clients.
  • Servers can handle various functions depending on their role: file storage, email management, web hosting, and database services.

Email Server

  • An email server is a server that handles and manages the sending, receiving, processing, and storage of emails.
  • Email servers ensure security protocols, store emails, and sort incoming and outgoing messages.

DNS Server

  • A DNS server converts user-friendly domain names into IP addresses necessary for locating computer services and devices worldwide.
  • This system is like the Internet’s phonebook, essential for the functionality of the global internet.


  • Routers are devices that forward data packets between computer networks, creating an overlay internetwork.
  • They manage traffic between home and office networks and the internet, determining the best route for data to travel efficiently.


  • A firewall is a network security device that monitors incoming and outgoing network traffic and decides whether to allow or block specific traffic based on a defined set of security rules.
  • It's a primary line of defence in network security, safeguarding internal networks from external threats.

Social and Ethical Issues in a Networked World

Privacy and Security

  • The advent of networked systems raises significant issues around data privacy and information security.
  • Concerns include the protection of personal data from unauthorised access, misuse, or cyber-attacks, and ensuring user confidentiality.

Digital Divide

  • The digital divide addresses inequalities in access to information technology, heavily influenced by geographic, economic, and socio-political factors.
  • It questions the fairness and accessibility of technology, highlighting the need for inclusive, global strategies to bridge this gap.

Environmental Impact

  • The environmental footprint of technology is a growing concern. This includes energy consumption of data centres, electronic waste, and the life cycle impact of producing and disposing of tech products.
  • Responsible use, recycling policies, and developing greener technologies are ethical considerations.

Dependence on Technology

  • Over-reliance on networked systems raises questions about vulnerability to system outages, data loss, and the erosion of traditional skills and privacy.
  • This dependency highlights the importance of backup systems, robust security protocols, and balanced integration of technology in daily life.

Misinformation and Censorship

  • In the era of information overload, the spread of misinformation and the role of censorship become crucial ethical concerns.
  • Balancing the freedom of information with the responsibility of providing accurate, verified content is a complex challenge in the digital age.

Labour and Employment

  • Technological advances, while creating new job opportunities, can also render certain skills obsolete.
  • Ethical challenges include workforce retraining, addressing unemployment due to automation, and ensuring fair labour practices in technology-driven economies.

These aspects underline the complexity and interdependence of computer systems in today's networked world. With technology evolving at a breakneck pace, it's critical for IT professionals and users alike to understand not only the technical components of computer systems but also the broader social, ethical, and economic impacts these technologies have on society and the environment.


Routers contribute significantly to the efficiency of a network by managing and directing data traffic. They determine the best route for data packets to reach their destination, which helps in reducing network congestion and enhancing overall transmission speed. Routers use routing tables and algorithms to make decisions on the most efficient paths for data transmission.

Moreover, routers can create and manage multiple networks and limit traffic between them based on security and administrative policies, thus organising and simplifying network traffic. They also facilitate network address translation (NAT), allowing multiple devices on a private network to share a single public IP address, conserving IP addresses and adding a layer of security. By segmenting networks, prioritising traffic, and enabling efficient resource use, routers play a pivotal role in optimising network performance.

Human resources are vital in managing and maintaining computer systems within an organisation. Their roles encompass a range of activities from system analysis, identifying organisational needs and how best to meet them through technology, to the actual implementation, maintenance, and support of these systems.

IT professionals ensure that the computer systems are not only running smoothly but also secure from cyber threats and compliant with relevant laws and policies. They also play a key role in training other employees, helping them make the most of the technology available to them. Additionally, in times of system failures or technological upgrades, IT human resources are critical in minimising downtime and ensuring a smooth transition. Effective human resource management in IT also includes strategic planning for future IT developments, aligning technology with business objectives, and managing the change associated with technology adoption within the organisation.

Technically, a network can operate without a DNS server, but it would be significantly less user-friendly and efficient. Without DNS servers, users would have to remember the IP addresses of every web server they wish to visit, which is impractical given the vast number of websites and the complexity of IP addresses.

DNS servers provide the essential service of translating domain names into IP addresses, which are required for routing traffic over the internet. Without this system, the usability of the global network would drastically decrease, impacting user experience and accessibility. Additionally, managing and remembering a large number of numeric IP addresses for various services and websites would be highly challenging for both users and network administrators, leading to potential errors and inefficiencies in network communication.

Email servers employ several methods to ensure the security and privacy of electronic messages. Firstly, they use Transport Layer Security (TLS) or its predecessor, Secure Sockets Layer (SSL), to encrypt emails during transit. This encryption prevents unauthorised parties from eavesdropping on email communications.

Additionally, email servers may use authentication mechanisms like Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) to verify the authenticity of the email source, thereby reducing the risk of email spoofing and phishing attacks.

For privacy, some email servers offer end-to-end encryption options, such as Pretty Good Privacy (PGP) or Secure/Multipurpose Internet Mail Extensions (S/MIME), which encrypt the email content itself. Only the sender and the intended recipient have the decryption keys, ensuring that even if an email is intercepted, its contents remain unreadable to anyone other than the intended recipient. Besides these, regular software updates and strong password policies are also integral to maintaining the security of email servers.

A firewall and an antivirus are both crucial for network security but serve different purposes. A firewall acts as a barrier between a trusted internal network and untrusted external networks, such as the Internet. It controls incoming and outgoing network traffic based on predetermined security rules and blocks certain traffic, depending on whether it is perceived as a threat. Firewalls can be hardware-based, software-based, or a combination of both.

In contrast, antivirus software is designed to detect, prevent, and remove malware from a computer system. While a firewall controls network traffic flow and blocks unauthorised access, an antivirus scans files and programs to identify and eliminate malicious software like viruses, worms, and trojans. Antivirus programs use a combination of signature-based, heuristic, and behaviour-based techniques to detect threats. Thus, while both tools aim to enhance security, firewalls primarily manage and filter network traffic, and antivirus software specifically targets malware.

Practice Questions

Explain the roles and functionalities of a DNS server and a router in a computer network.

A DNS server, or Domain Name System server, plays a crucial role in translating user-friendly domain names (like www.example.com) into numerical IP addresses that computers use to identify each other on the network. When a user types a web address into their browser, the DNS server resolves this address to the IP address of the server hosting the website, facilitating user navigation on the internet.

A router, on the other hand, directs data packets between different networks, ensuring that information sent from a device reaches its correct destination. It analyses the data packets' destination IP addresses and uses this information, along with complex routing algorithms, to determine the most efficient path for the packet to travel. Routers are fundamental in connecting multiple networks and managing traffic in both local networks (LANs) and wider networks (WANs), including the internet.

Discuss the ethical implications of the digital divide highlighted by the development of networked computer systems.

The digital divide refers to the inequality in access to digital technology and internet connectivity among different groups of people, influenced by factors like geography, economic status, and educational levels. The ethical implications of the digital divide are profound, as it can exacerbate social and economic inequalities. Those without adequate access to technology are disadvantaged in terms of obtaining information, participating in the digital economy, and accessing educational or governmental services online. This divide challenges the equitable distribution of resources and opportunities in a digital era, highlighting the need for policies that promote inclusive access to technology and the internet, ensuring that the benefits of digital advancement are shared broadly across all societal segments. Addressing the digital divide is essential not only for fairness but also for harnessing a diverse range of talents and perspectives necessary for innovation and societal progress.

Alfie avatar
Written by: Alfie
Cambridge University - BA Maths

A Cambridge alumnus, Alfie is a qualified teacher, and specialises creating educational materials for Computer Science for high school students.

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