Class 8 Computer Notes: Computer Networking and Security

Class 8 Computer Notes

Chapter 1: Computer Networking and Security

📡 What is Networking?

➥ Networking means connecting two or more computers to share data, files, and resources like printers and the internet.

eg Computers connected in a school computer lab form a network.

🖥️ What is a Computer Network?

➥ Computer Network is a group of interconnected computers that can communicate with each other.

➯ hese networks help us to communicate, share resources, and access information easily.

✅ Advantages of Computer Networks

1. File Sharing: Easily send or receive files between computers.
2. Resource Sharing: Use printers, internet, or software from any connected computer.
3. Fast Communication: Chat, email, or video call in no time.

❌ Disadvantages of Computer Networks

1. Security Issues: Risk of virus attacks and hacking.
2. High Cost: Initial setup and maintenance can be expensive.
3. Network Failure: If the network is down, all connected devices stop working together.

🔗 Classification of Computer Networks

1. PAN (Personal Area Network) - Small network for personal devices (e.g., Bluetooth between phone and laptop).



2. LAN (Local Area Network) - Network in a small area like a school or office building.



3. MAN (Metropolitan Area Network) - City-wide connection.

4. WAN (Wide Area Network) - Large geographical area like internet.

🛠️ Devices Used in a Network

1. Router: Connects different networks and sends data between them.
2. Switch: Connects devices within a network and shares data among them.
3. Hub: Sends data to all devices in the network (less smart than a switch).
4. Modem: Connects the network to the internet.
5. NIC (Network Interface Card): A card inside the computer that helps it connect to a network.

🔄 Network Topologies

1. Bus Topology: All computers are connected using a single cable.

2. Star Topology: All computers are connected to a central device like a switch or hub.

3. Ring Topology: Computers are connected in a circle. Data moves in one direction.

4. Mesh Topology: Each computer is connected to every other computer in the network.

📶 Data Transmission Media

1. Wired (Bounded) Media:

1. Twisted Pair Cable: Used in homes and offices.
2. Coaxial Cable: Used for cable TV and internet.
3. Optical Fiber: Very fast and used for long-distance connections.

2. Wireless (Unbounded) Media:

1. Bluetooth: Short-range connection for phones, speakers, etc.
2. Wi-Fi: Connects devices to the internet wirelessly.

🗂️ Accessing Shared Networks

➥ Users can access shared folders, files, and printers over the network easily and securely.

🔒 Network Security

1. Use Strong Passwords: Never use easy-to-guess passwords.
2. Install Antivirus: To protect from viruses and malware.
3. Use Firewalls: To block unwanted access to your computer.
4. Update Software: Always keep your system updated to fix bugs and security holes.

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Computer Networks Worksheet

A. Tick (✔) the correct option:

1. The device that distributes a network connection to all the computers in the network: ✔ c. Both (a) and (b)
2. Which of the following can be used to connect two separate LANs? ✔ b. Router
3. A ________ can be set up for a city: ✔ c. MAN
4. The cables that use light beams through a glass-bound fiber to transmit data: ✔ c. fiber optic cables
5. Which statement is not correct? ✔ a. A computer network is always secure.

B. Fill in the blanks with suitable words:

1. A number of devices arranged together in order to exchange data and information constitutes a network.
2. Computers are mostly connected through cables in a system called a wired network.
3. The server manages and controls other devices connected to the network.
4. The NIC is also called an Ethernet card.
5. The fiber optic cables provide the highest data transmission speed.
6. The Wi-Fi works on wireless radio frequency technology.

C. Write 'T' for True and 'F' for False:

1. You can share data files around the computers connected to the network. — T
2. Wireless networks are usually used in small LANs. — T
3. PANs are set up for personal use only. — T
4. Client-server networks specifically consist of a server and other systems. — T
5. A switch is like a hub with advanced features. — T

D. Answer the following questions:

1. What do you mean by a computer network?
   A computer network is a collection of interconnected computers and other devices that can share resources and data with each other.
2. How can you classify computer networks on the basis of the role of a computer in the network?
   Computer networks can be classified as Peer-to-Peer and Client-Server based on their role.
3. Define network topology. What are the different types of network topologies?
   Network topology is the arrangement of different elements (links, nodes, etc.) in a computer network. Types: Star, Ring, Bus, Mesh, Tree.
4. What is the difference between the bounded and unbounded transmission media?
   Bounded media use physical cables (e.g., coaxial, twisted pair), while unbounded media transmit data wirelessly (e.g., radio waves, microwaves).
5. State some ways to protect a wired or wireless computer network from possible threats.
   Use of firewalls, antivirus software, strong passwords, encryption, disabling unused ports, and regular software updates.

E. Define the following terms:

1. Nodes: Devices like computers, printers, etc., connected to a network.
2. Cables: Physical media used to connect network devices for data transmission.
3. Hub: A device used to connect multiple network devices, transmitting data to all connected devices.
4. Server: A powerful computer that provides resources and services to other computers (clients) on the network.
5. Wi-Fi: A wireless technology that allows devices to connect to a network using radio waves.

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