Computer Networks

 Computer Networks

Definition: A computer network is a system that allows two or more computers to communicate and share data, hardware, and applications.

A computer network is a system that connects two or more computing devices for transmitting and sharing information. Computing devices include everything from a mobile phone to a server. These devices are connected using physical wires such as fiber optics, but they can also be wireless.  

The first working network, called ARPANET, was created in the late 1960s and was funded by the U.S. Department of Defense. Government researchers used to share information at a time when computers were large and difficult to move. We have come a long way today from that basic kind of network. Today’s world revolves around the internet, which is a network of networks that connects billions of devices across the world. Organizations of all sizes use networks to connect their employees’ devices and shared resources such as printers.  

An example of a computer network at large is the traffic monitoring systems in urban cities. These systems alert officials and emergency responders with information about traffic flow and incidents. A simpler example is using collaboration software such as Google Drive to share documents with colleagues who work remotely. Every time we connect via a video call, stream movies, share files, chat with instant messages, or just access something on the internet, a computer network is at work.  

Computer networking is the branch of computer science that deals with the ideation, architecture, creation, maintenance, and security of computer networks. It is a combination of computer science, computer engineering, and telecommunications.


Types of Computer Networks:

LAN (Local Area Network)  

  • Small area (like a home, office, or school). 
  • Example: All computers in a school are connected to one printer.  

WAN (Wide Area Network)  

  • Covers large geographical areas (like countries). 
  • The Internet is the largest WAN.  

MAN (Metropolitan Area Network)  

  • Covers a city or campus  
  • Example: A Network connecting different branches of a university in a city.  

PAN (Personal Area Network)  

  • Very small network (like around one person). 
  • Example: Your phone is connected to your laptop via Bluetooth.

LAN (Local area network)

A local area network (LAN) is a group of computers and peripheral devices that are connected together within a distinct geographic area, such as an office building or campus. The devices are connected via a common communications line or wireless connection to a server.  A LAN may serve as few as two or three users in a home office or thousands of users in a corporation's central office. Homeowners and IT administrators set up LANs so that network nodes can communicate and share resources, such as printers or network storage.  
A LAN includes various network components, such as cables, switches, routers, firewalls, load balancers, and wireless access points (WAPs). It can be connected to a wide range of network devices, such as game consoles, servers, desktop and laptop computers, printers, and Internet of Things (IoT) devices.

WAN (Wide Area Network) 

A wide-area network (WAN) is the technology that connects your offices, data centers, cloud applications, and cloud storage together. It is called a wide-area network because it spans beyond a single building or large campus to include multiple locations spread across a specific geographic area, or even the world. For example, businesses with many international branch offices use a WAN to connect office networks together. The world’s largest WAN is the Internet because it is a collection of many international networks that connect to each other. This article focuses on enterprise WANs and their uses and benefits.

MAN (Metropolitan Area Network)

A metropolitan area network (MAN) is a computer network that connects computers within a metropolitan area, which could be a single large city, multiple cities and towns, or any given large area with multiple buildings. A MAN is larger than a local area network (LAN) but smaller than a wide area network (WAN). MAN does not have to be in urban areas; the term "metropolitan" implies the size of the network, not the demographics of the area that it serves.

PAN (Personal Area Network)

The average person is surrounded by a web of connected devices all day long. Your phone, your computer, your speakers, and even your appliances are capable of reaching out to one another. A PAN makes that possible.   For example, your home office likely contains a PAN. A cord connects your computer to your printer. And wireless headphones connect you with the audio of the Zoom meeting you're attending on your computer.

Key Components: 

  • Router: Directs data between networks.  
  • Switch: Connects devices within a LAN.  
  • Modem: Converts signals for internet access.  
  • Cables/Wi-Fi: Transmit data physically or wirelessly.

Protocols: 

  • Networks work based on standard rules called protocols. 
  • The most common:  TCP/IP – Foundation of the internet.  
  • HTTP/HTTPS – Used for browsing web pages.  
  • FTP – For transferring files.  
  • DNS – Converts website names to IP addresses.

Network Devices

Network devices or nodes are computing devices that need to be linked to the network. Some network devices include:  
  • Computers, mobiles, and other consumer devices: These are end devices that users directly and frequently access. For example, an email originates from the mailing application on a laptop or mobile phone. 
  • Servers: These are application or storage servers where the main computation and data storage occur. All requests for specific tasks or data come to the servers. 
  • Routers: Routing is the process of selecting the network path through which the data packets traverse. Routers are devices that forward these packets between networks to ultimately reach the destination. They add efficiency to large networks. 
  • Switches: Repeaters are to networks what transformers are to electricity grids—they are electronic devices that receive network signals and clean or strengthen them. Hubs are repeaters with multiple ports. They pass on the data to whichever ports are available. Bridges are smarter hubs that only pass the data to the destination port. A switch is a multi-port bridge. Multiple data cables can be plugged into switches to enable communication with multiple network devices. 
  • Gateways: Gateways are hardware devices that act as ‘gates’ between two distinct networks. They can be firewalls, routers, or servers.

Main Purposes of Computer Networks 

  • Communication: Sending emails, video calls, messaging, etc.  
  • Resource Sharing: Accessing shared files, printers, or software.  
  • Data Access and Management: Centralized data storage and database access.  
  • Remote Access: Allowing users to work from different locations.

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