Class 10 Computer Science Unit 1: Computer Network and Communication

1. Fundamentals of Networking and Telecommunication
   A computer network consists of two or more computers and devices connected to share data, resources, and messages. These connections can be wired (like Ethernet) or wireless (like Wi-Fi and Bluetooth). Networks are essential in the digital world for activities such as email, video calls, online study, and working from home.

2. Telecommunication refers to the process of sending and receiving information over long distances using electronic devices like phones, radios, and computers.

3. Key Networking Concepts

• Broadband: Broadband is a type of high-speed internet connection that allows a large amount of data to be transmitted quickly and continuously over a network. DSL (telephone lines), Cable (TV cables), Fiber-optic (glass wires), Satellite, and Wireless (4G/Wi-Fi).

• Throughput vs. Bandwidth: Bandwidth is the maximum amount of data a network can carry at once, while throughput is the actual amount of data successfully sent or received in a given time. Both are measured in bits per second (bps), Mbps, or Gbps.

• 3G: A mobile network that provides basic internet with moderate speed.
  4G: A faster mobile network that supports high-speed internet and HD streaming.
  5G: The latest mobile network offering extremely fast speed and very low delay.

• Frequency: The number of times the signal waves goes up and down in a second, High frequency- More data sent, Less frequency- Less data sent usually in kHz, MHz, or GHz. It is vital for technologies like Wi-Fi (2.4 GHz) and mobile networks.

• Data Packets: Data packets are small units of data that are broken down from a larger file and sent separately over a network, then reassembled at the destination.

1. Data Communication Modes

• Simplex: Data flows in only one direction (e.g., radio, television).

• Half-Duplex: Data flows in both directions, but only one at a time (e.g., walkie-talkies).

• Full-Duplex: Data flows in both directions simultaneously (e.g., mobile phones).

1. Communication Media - The data transmission path or wireless system through which data is transmitted from one device to another in a network.

• Guided (Wired) Media: Uses physical cables.
    - CAT6: Twisted-pair network, to carry data fast and efficiently. Supports speeds up to 1 Gbps over 100 meters and reduces interference.

• Consists: Outer jacket (protection from physical damage), Twisted pairs oof copper wires (reduces signal interference) Separator (seprates twisted pairs & signal interferance) Types: 1. Shielded: surrounded by a metallic shield 2. Unshielded: no additional shielding.
    - Optical Fiber: Uses light pulses to transmit data at extremely high speeds through glass or plastic strands, carries large amount of data quickly.

• Structure- Outer Jacket (covers the fiber against damages), Strength member (gives strenght to the fiber), Coating (work as cushion to protect from scratches) Claddding (keeps signal inside core), Core (light signals travels to carry data)

• Unguided (Wireless) Media: Uses radio waves.
    - Wi-Fi: A wireless network media that provides a connection between a computer and the internet without using cables.
    - Bluetooth: A short-range wireless technology that allows devices to exchange data over short distance using Frequency Hopping Spread Spectrum (FHSS).
    - RFID: RFID (Radio Frequency Identification) is a technology that uses radio waves to identify and track objects wirelessly.
    - Satellite: A kind of wireless technology in which signals are sent and received through satellites positioned in space.

• Two parts: 1. Space segment- real satellite, rotates around the earth.

• 2. Ground segment- Stations, transmits the signal.

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  Basis	Wired Media	Wireless Media
  Definition	Transmission of data through physical cables	Transmission of data without cables using signals
  Medium	Uses wires like twisted pair, coaxial, fiber optic	Uses air (radio waves, microwaves, infrared)
  Speed	Generally faster and stable	Usually slower and can vary
  Reliability	More reliable, less interference	Less reliable, more interference
  Mobility	Limited (fixed connection)	High mobility (can move freely)
  Cost	Higher installation cost	Lower installation cost

1. Hardware: Connectors and Networking Devices

• Connectors: Connectors are devices used to join two or more cables or components to enable the transmission of data or signals.
    - RJ-45: RJ-45 (Registered Jack-45) is a type of connector used to connect Ethernet cables in computer networks. 8 metal pins & 8 twisted wires.
    - Media Converter: Media converter is a device that converts one type of transmission media or signal into another, such as from electrical signals to optical signals.

• Networking components: The hardware devices used to build and operate a computer network, enabling communication and data sharing between devices.

• Types: Software component, Hardware component.

• Software components: The programs or applications that help manage, control, and operate a computer system or network.

Devices: Hardware components are the physical parts of a computer or network that can be seen and touched, used to perform operations and support communication.
  - Repeater: Regenerates weak signals for long-distance transfer.
  - Hub: Connects multiple computers in a star topology but is generally less efficient than a switch.
  - Switch: An intelligent device that joins computers and coordinates data flow faster than a hub.
  - Bridge: Interconnects two networks using similar protocols.
  - Router: An intelligent device that determines the best path for data using IP addresses.

1. Network Topology- Network topology is the physical and logical arrangement in which computers and devices are arranged and connected in a network.

• Bus Topology is a type of network layout in which all devices are connected to a single main cable called the backbone.

  Key features:

  • All devices share a single communication line (backbone cable).

  • If the main cable fails, the whole network stops working.

  • It is simple and inexpensive to set up.

• Star Topology is a network structure in which all devices are connected to a central device like a hub or switch.

  Key features:

  • All data passes through a central device (hub/switch).

  • If one device fails, it does not affect the whole network.

  • Easy to manage and expand by adding new devices.

• Ring Topology is a network structure in which all devices are connected in a circular path, and data travels in one direction (or both in some cases) from one device to another.

  Key features:

  • Each device is connected to exactly two other devices, forming a ring.

  • Data passes through each device until it reaches the destination.

  • If one connection breaks, the whole network can be affected.

• Hybrid Topology is a type of network topology that combines two or more different topologies (like star, bus, or ring) in a single network.

  Key features:

  • Combines advantages of different topologies.

  • Flexible and can be designed according to network needs.

  • More reliable, but more complex and expensive to set up.

1. Computer network is a system in which two or more computers and devices are connected together to share data, resources, and communicate with each other.

   Features:

   • Allows sharing of files, printers, and internet connection.

   • Enables fast communication between users through email, chat, etc.

   • Can connect devices over small areas (LAN) or large areas (WAN).

• Coverage-Based Categories:
    - PAN (Personal Area Network): PAN is a small network used to connect devices within a very short range, usually around one person.

  Features:

  • Very small coverage area (around 1–10 meters).

  • Connects personal devices like mobile, laptop, headset, and smartwatch.

  • Uses technologies like Bluetooth or USB for communication.
      - LAN (Local Area Network): LAN is a network that connects computers and devices within a small area like a room, building, or school.

    Features:

    • Covers a small geographical area.

    • Provides high-speed data transfer.

    • Allows sharing of resources like files, printers, and internet.

    • MAN (Metropolitan Area Network): MAN is a network that connects multiple LANs within a large area like a city or town.

      Features:

      • Covers a larger area than LAN but smaller than WAN.

      • Connects networks within a city or metropolitan area.

      • Provides fast communication between different LANs.

      • WAN (Wide Area Network): WAN is a network that connects computers and smaller networks over a very large geographical area like countries or continents.

        Features:

        • Covers a very large area (national or global).

        • Connects multiple LANs and MANs together.

        • Uses communication technologies like satellites, leased lines, and internet.

• Network Architecture: Network architecture is the design and structure of a computer network that shows how computers and devices are connected and how data is communicated between them.
   Client-Server: A network model in which client devices request services or data, and a central server provides those services or data.

  Features:

  • Centralized system where the server controls resources and data.

  • Clients depend on the server to access services like files, websites, or applications.

  • Easy to manage, secure, and suitable for large networks.

  • Peer-to-Peer: (P2P) architecture is a network model in which all computers are equal and can directly share data and resources with each other without a central server.

    Features:

    • No central server; all devices act as both client and server.

    • Easy and cheap to set up for small networks.

    • Each computer can directly share files and resources with others.

1. Protocols and IP Addressing

• Protocols: Rules and standards that device follows for communication. Examples include TCP/IP (Internet), HTTP/HTTPS (Web), DHCP (Auto-IP assignment), SMTP (Email), and FTP (File transfer).

• IP Addressing:
    - IPv4: Uses 32-bit decimal addresses (e.g., 192.168.1.1).
    - IPv6: Uses 128-bit hexadecimal addresses to solve the problem of address exhaustion.

Default gateway is a device (usually a router) that connects a local network to other networks or the internet, allowing data to be sent outside the local network.

Roles of default gateway:

• It connects a local network to other networks or the internet.

• It forwards data packets from the local network to the correct destination outside the network.

• It acts as an entry and exit point for all network traffic.

• Network command line utilities are tools used in the command prompt to check, test, and troubleshoot network connections and settings.

• Here are the common network command line utilities with full forms and definitions:

  1. PING (Packet Internet Groper)
  It is used to check whether a computer or website is reachable and to measure the time taken for data to travel and return.

  2. IPCONFIG (Internet Protocol Configuration)
  It is used to display and manage the IP address, subnet mask, and default gateway of a computer.

  3. TRACERT (Trace Route)
  It shows the path taken by data packets from the source computer to the destination, including all intermediate routers.

  4. NSLOOKUP (Name Server Lookup)
  It is used to find the IP address of a domain name or the domain name of an IP address using DNS.

1. Internet, Intranet, and Extranet

• Internet: A public, global network of networks accessible to everyone.

• Benefits:

  • Provides global communication and access to information.

  • Supports online services like education, banking, shopping, and entertainment.

  • Easy and fast sharing of data worldwide.

  Limitations:

  • Security risks like hacking and viruses.

  • Can lead to misuse and addiction.

  • Information may not always be reliable.

• Intranet: A private network restricted to employees within a single organization.

• Benefits:

  • Secure network for internal organization use.

  • Easy sharing of files, data, and communication within an organization.

  • Faster and more efficient than the internet for internal work.

  Limitations:

  • Limited to organization only (not accessible from outside).

  • Expensive to set up and maintain.

  • Requires technical support for management

• Extranet: A private network that allows controlled access to authorized external partners like suppliers or clients.

• Benefits:

  • Allows controlled access to outsiders (like suppliers or customers).

  • Improves business communication and collaboration.

  • Secure sharing of specific information with external users.

  Limitations:

  • Security risks if not properly managed.

  • More complex to set up than intranet.

  • Requires strict user access control and maintenance.

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    Internet	Intranet	Extranet
    A global network of computers used worldwide.	A private network used within an organization.	A controlled network that allows outside users limited access to an organization’s system.
    Open to everyone across the world.	Accessible only to members of the organization.	Accessible to authorized external users like customers or suppliers.
    Used for communication, information sharing, and online services globally.	Used for internal communication and sharing resources within an organization.	Used for secure business communication and collaboration with external parties.