Understanding Computer Networks: Types, Elements, and Security

Posted on Aug 26, 2024 in Computers

Types of Networks

Networks can be classified based on the number of connected computers and their geographical reach:

Local Area Network (LAN)

LANs connect computers within a limited area, such as a room or building.

Wide Area Network (WAN)

WANs connect computers across a larger geographical area, spanning regions, countries, or even multiple countries.

Network Architectures

Networks can be categorized based on their architecture and the roles of computers:

Client-Server Network

In this architecture, a central computer, the server, provides resources to other computers, the clients.

Peer-to-Peer Network

In this architecture, there is no central server. All connected computers, or peers, can share resources with each other.

Elements of a Network

A. Transmission Media

This refers to the hardware used to transmit data across the network:

  • Cable:
    • Twisted Pair: Copper cable with four twisted pairs of wires, commonly used with RJ-45 connectors.
    • Coaxial Cable: Copper core with insulation and a metal mesh to prevent interference.
    • Fiber Optic: Thin glass filaments that transmit data using light pulses, offering the fastest data transmission speeds.
  • Wireless: Data is transmitted through the air via radio waves.

B. Network Devices

  • Network Card (NIC): A circuit board installed in a computer, enabling it to connect to a network.
  • Network Connection: The configuration that allows a computer to communicate with other devices on the network.
  • Linking Devices: Used to connect multiple network devices:
    • Hub: A simple device that broadcasts data to all connected devices.
    • Switch: A more intelligent device that sends data only to the intended recipient.

Wireless Networks

To connect to a wireless network, a computer needs a wireless network adapter:

  • PCI Adapter: Installed on the motherboard, with an external antenna.
  • PCMCIA Adapter: A compact card for laptops.
  • USB Adapter: Resmbles a flash drive and connects to a USB port.

Internet

Several ways exist to connect to the internet:

  • Public Switched Telephone Network (PSTN): Uses a modem to convert analog signals to digital and vice versa.
  • Integrated Services Digital Network (ISDN): Transmits data digitally for faster speeds.
  • Asymmetric Digital Subscriber Line (ADSL): Uses the phone line for high-speed data transmission.

World Wide Web

The Web uses hypertext documents, or web pages, written in HTML. These pages contain hyperlinks that allow users to navigate to other resources. Web pages are stored on web servers, which use the HTTP protocol for communication. URLs identify specific web pages.

Virtual Communities and Online Platforms

  • Virtual Community: A group of people who interact online.
  • Social Networking: Websites that facilitate online communication and interaction.
  • Wikis: Collaborative websites where users can contribute and edit content.
  • Blogs: Online journals or platforms for sharing information and opinions.
  • BSCW (Basic Support for Collaborative Work): Shared workspaces for online collaboration.

Computer Security

Computer security aims to ensure integrity, confidentiality, and availability of data:

  • Integrity: Prevents unauthorized modification of information.
  • Confidentiality: Prevents unauthorized access to information.
  • Availability: Ensures authorized users can access resources when needed.

Threats to Computer Security

  • Virus: Malicious software that spreads and can cause harm.
  • Trojan: Disguised as legitimate software, but carries a hidden malicious payload.
  • Spyware: Secretly collects information from a computer.
  • Spam: Unsolicited bulk email, often used for advertising or phishing.

Security Measures

  • Back up data regularly.
  • Exercise caution with email and instant messaging.
  • Avoid opening unknown messages or attachments.
  • Avoid downloading files from untrusted sources.
  • Use legal software.
  • Install an antivirus program.
  • Scan removable storage devices.
  • Install a firewall.

Antivirus Software

Antivirus programs detect, block, and remove computer viruses by comparing files against a database of known viruses.