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3.4 Networks and the Internet

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Types of Computing Networks

  • Connection type:
    • Wired: Networks using physical cables to connect devices.
      • Ethernet: Most common wired network standard using twisted pair, coaxial, or fiber optic cables.
    • Wireless: Networks using radio waves to connect devices without physical cables.
      • Wi-Fi: Wireless local area network (WLAN) based on IEEE 802.11 standards.
      • Bluetooth: Short-range wireless technology for connecting devices.
      • Cellular: Wireless networks for mobile devices using 3G, 4G, or 5G technologies.
  • By size:
    • Personal Area Network (PAN): Small network for interconnecting devices within a person's workspace.
    • Local Area Network (LAN): Network connecting devices within a limited area, such as a home, office, or building.
    • Metropolitan Area Network (MAN): Network spanning a city or metropolitan area.
    • Wide Area Network (WAN): Network extending over a large geographical area, connecting multiple LANs and MANs.
  • By type:
    • Client-Server: Network model where clients request resources and services from a central server.
    • Peer-to-Peer (P2P): Decentralized network model where each device acts as both a client and a server.

Components of Computing Networks

  • Client: Device that requests resources or services from a server.
  • Server: Computer that provides resources, services, or information to clients.
  • Modem: Device that converts digital signals to analog signals (modulation) and vice versa (demodulation) for transmission over telephone lines or cable networks.
  • Router: Device that forwards data packets between networks, determining the best path for data to travel.
  • Switch: Device that connects multiple devices on a network and filters/forwards data packets to the intended destination.
  • Hub: Simple device that broadcasts data packets to all connected devices, without filtering or directing traffic.
  • Channels: The medium through which data is transmitted, such as cables, radio waves, or optical fibers.
  • Network Interface: Hardware component that enables a device to connect to a network, such as a network interface card (NIC) or wireless network adapter.

Characteristics of Computing Networks

  • Standards and Protocols: Rules and conventions that govern communication between devices on a network.
    • Interoperability: The ability of different systems and devices to communicate and work together seamlessly.
    • Domain Names: Human-readable names (e.g., www.example.com) that are translated into IP addresses.
    • Addresses: Unique identifiers assigned to devices on a network, such as IP addresses or MAC addresses.
  • Security: Measures to protect networks and data from unauthorized access, misuse, or damage.
    • Identification: Verifying the identity of a user or device.
    • Authentication: Confirming the identity of a user or device.
    • Encryption: Converting data into a coded format to prevent unauthorized access.
    • Firewall: A system that monitors and controls incoming and outgoing network traffic based on predetermined security rules.
    • Proxy Server: An intermediary server that acts on behalf of clients, forwarding requests and responses.
    • VPN (Virtual Private Network): A secure, encrypted connection between two networks or devices over the internet.
    • Security Layers: Different levels of security measures applied at various points in a network, such as physical, network, and application layers.
  • Capacity: The ability of a network to handle data traffic and maintain performance.
    • Bandwidth: The maximum amount of data that can be transmitted over a network connection in a given time period.
    • Data Compression: Reducing the size of data to improve transmission speed and efficiency.
    • Net Neutrality: The principle that internet service providers should treat all data equally, without discriminating or charging differently based on content, user, platform, or application.
  • Infrastructure: The physical and organizational structures that support the operation of a network.
    • Internet Backbone: The main data routes between large, interconnected networks and core routers on the internet.

Computing Network Providers and Services

  • Providers:
    • Internet Service Provider (ISP): A company that provides internet access to customers.
  • Services: Applications and resources available over a network.
    • Chat: Real-time text-based communication between users.
    • Texting: Sending short text messages between mobile devices.
    • Email: Sending and receiving electronic messages over the internet.
    • File Sharing: Allowing users to share and access files over a network.
    • VOIP (Voice Over Internet Protocol): Making voice calls using an internet connection instead of a traditional phone line.
    • Online Messaging: Instant messaging services that allow users to communicate in real-time over the internet.
    • Hosting: Providing storage, computing resources, and services for websites and applications.
    • Video Conferencing: Conducting real-time video meetings and discussions over the internet.

The World Wide Web

  • Distinct from the Internet: The World Wide Web is an information system accessible over the internet, while the internet is the global network infrastructure.
  • URL (Uniform Resource Locator): The address of a web page or resource on the World Wide Web.
  • HTTP (Hypertext Transfer Protocol): The protocol used for transmitting web pages and other content over the internet.
  • Browser: A software application used to access and view websites.
  • The World Wide Web Consortium (W3C): An international organization that develops web standards and guidelines.

Evolution of the Internet and the Web

  • Innovations in early development: Key milestones and breakthroughs that shaped the internet and the web.
    • ARPANET: The precursor to the internet, developed by the US Department of Defense.
    • TCP/IP: The communication protocols that enable devices to communicate over the internet.
    • World Wide Web: Invented by Tim Berners-Lee, providing a user-friendly interface for accessing information on the internet.
  • Rise of online social media platforms: The emergence and growth of social networking sites like Facebook, Twitter, and Instagram.
  • Internet of Things (IoT) and ubiquitous networking: The interconnection of everyday devices and objects through the internet, enabling them to send and receive data.

Internet Dilemmas

  • Surveillance: Monitoring online activities and collecting data on individuals or groups.
  • Personal data: Information that can be used to identify an individual, such as name, address, or online behavior.
  • Privacy: The right to control one's personal information and maintain confidentiality online.
  • Anonymity: The ability to use the internet without revealing one's identity.
  • The right to be forgotten: The concept that individuals should be able to request the removal of their personal information from internet searches and databases.
  • Cybercrime: Criminal activities carried out using computers, networks, or the internet.
    • Hacking: Unauthorized access to computer systems or networks.
    • Viruses: Malicious software designed to replicate and spread, causing damage or disruption to computer systems.
    • Spam: Unsolicited or unwanted electronic messages, often sent in bulk.
    • Spyware: Software that collects information about a user's computer activities without their knowledge.
    • Identity Theft: Fraudulently acquiring and using another person's personal information for financial gain or other purposes.
    • Social Engineering: Manipulating individuals to divulge confidential information or perform actions that compromise security.
    • Ransomware: Malware that encrypts a victim's files and demands a ransom payment for the decryption key.
    • Denial of Service: An attack that overwhelms a network or server with traffic, making it unavailable to users.
  • Dark Web: A portion of the internet that is only accessible through specialized software, often used for illegal activities.
  • Trolling: Deliberately provocative or offensive online behavior intended to disrupt conversations or upset others.