A computer network is a collection of interconnected devices that share resources and information. These devices can include computers, servers, printers, and other hardware. Networks allow for the efficient exchange of data, enabling various applications such as email, file sharing, and internet browsing.

Basic Terminologies of Computer Networks

• Network: A group of connected computers and devices that can communicate and share data with each other.
• Node: Any device that can send, receive, or forward data in a network. This includes laptops, mobiles, printers, earbuds, servers, etc.
• Networking Devices: Devices that manage and support networking functions. This includes routers, switches, hubs, and access points.
• Transmission Media: The physical or wireless medium through which data travels between devices.
• Wired media: Ethernet cables, optical fiber.
• Wireless media: Wi-Fi, Bluetooth, infrared
• Service Provider Networks: Networks offered by external providers that allow users or organizations to lease network access and capabilities. This includes internet providers, mobile carriers, etc.

How Does a Computer Network Work

Basics building blocks of a Computer network are Nodes and Links.

• Network Node: Any device in a network, such as a modem, router, or computer, that sends or receives data.
• Link: The medium that connects nodes, like cables, wires, or wireless signals.
• Working: Networks use rules called protocols to send and receive data between devices. Each device is identified by a unique IP Address.
• Firewall: A security tool (hardware or software) that monitors traffic. Based on set rules, it either allows, blocks, or drops data.

Types of Computer Network Architecture

Computer Network falls under these broad Categories:

• Client-Server Architecture:Client-Server Architecture is a type of Computer Network Architecture in which Nodes can be Servers or Clients. Here, the server node can manage the Client Node Behaviour.
• Peer-to-Peer Architecture: In P2P (Peer-to-Peer) Architecture, there is not any concept of a Central Server. Each device is free for working as either client or server.

Network Devices

An interconnection of multiple devices, also known as hosts, that are connected using multiple paths for the purpose of sending/receiving data or media. Computer networks can also include multiple devices/mediums which help in the communication between two different devices; these are known as Network devices and include things such as routers, switches, hubs, and bridges. 

Various Network devices are:

1. Router

• Connects multiple networks (like home network to the internet).
• Directs data packets to their correct destination.

2. Switch

• Connects devices within a network (like computers in an office).
• Forwards data only to the specific device it is meant for.

3. Hub

• Basic device that connects multiple devices in a network.
• Sends data to all devices (less efficient than a switch).

4. Bridge

• Connects and filters traffic between two networks or segments.
• Helps reduce network traffic.

5. Gateway

• Connects two different types of networks.
• Translates data between different protocols.

6. Access Point (AP)

• Provides wireless connectivity to devices.
• Extends a wired network into a Wi-Fi network.

7. Modem

• Converts digital data from a computer into signals for phone/cable lines and vice versa.
• Provides internet access.

8. Firewall

• Monitors and controls incoming and outgoing network traffic.
• Provides security by blocking unauthorized access.

Goals of Networks

• Convenience: Make computer use easier for users.
• Efficiency: Manage hardware resources effectively for better performance.
• Resource Management: Allocate CPU, memory, I/O, and storage fairly and efficiently.
• Security & Protection: Protect data and resources from unauthorized access.
• Reliability & Fault Tolerance: Ensure system runs smoothly and recovers from failures.
• Scalability: Support growth in users, processes, and resources.

Uses of Computer Networks

• Communication: Email, chat, and video conferencing.
• Resource Sharing: Share printers, scanners, and files to save cost and effort.
• Remote Access: Access data and systems from anywhere.
• Collaboration: Work together on projects, share ideas, and review work.
• E-commerce: Enable online shopping and secure payments.
• Education: Support online learning, research, and student–teacher collaboration.

Characteristics of Computer Networks

1. Security

• Protects data from unauthorized access, hacking, and viruses.
• Uses tools like firewalls, encryption, and authentication to ensure safety.

2. Reliability

• Ensures data and resources are always available.
• Redundancy and backups keep the network running during failures.

3. Scalability

• The ability to grow and handle more devices/users without performance loss.
• Example: The internet supports millions of new users daily.

4. High Performance

• Fast data transfer, low latency, and high throughput improve user experience.
• Performance depends on bandwidth, response time, and processing power.

5. Quality of Service (QoS)

• Prioritizes important data for faster delivery.
• Ensures smooth communication, especially for streaming and video calls.
  

Introduction to Computer Networks

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