All the computers in this type of network are connected to two other computers.

computer network, two or more computers that are connected with one another for the purpose of communicating data electronically. Besides physically connecting computer and communication devices, a network system serves the important function of establishing a cohesive architecture that allows a variety of equipment types to transfer information in a near-seamless fashion. Two popular architectures are ISO Open Systems Interconnection (OSI) and IBM’s Systems Network Architecture (SNA).

Two basic network types are local-area networks (LANs) and wide-area networks (WANs). LANs connect computers and peripheral devices in a limited physical area, such as a business office, laboratory, or college campus, by means of links (wires, Ethernet cables, fibre optics, Wi-Fi) that transmit data rapidly. A typical LAN consists of two or more personal computers, printers, and high-capacity disk-storage devices called file servers, which enable each computer on the network to access a common set of files. LAN operating system software, which interprets input and instructs networked devices, allows users to communicate with each other; share the printers and storage equipment; and simultaneously access centrally located processors, data, or programs (instruction sets). LAN users may also access other LANs or tap into WANs. LANs with similar architectures are linked by “bridges,” which act as transfer points. LANs with different architectures are linked by “gateways,” which convert data as it passes between systems.

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WANs connect computers and smaller networks to larger networks over greater geographic areas, including different continents. They may link the computers by means of cables, optical fibres, or satellites, but their users commonly access the networks via a modem (a device that allows computers to communicate over telephone lines). The largest WAN is the Internet, a collection of networks and gateways linking billions of computer users on every continent.

Computer Network links two or more computing devices and the computing hardware through various communication channels (i.e. cables, telephone lines, radio waves, wifi, etc.) for data and resource sharing. For example, Bluetooth connection to transfer files, a hotspot for sharing the internet, etc.

A network could be small, inclusive of only one system, or as large as one may need.

Need for Computer Network

• Resource Sharing- One can use a single resource to be shared along with multiple computers. i.e. In an organization, we can use a single printer for various computers.
• Information Sharing- One can share information with the help of networking.
• Communication- Ease of messaging.
  
  

Types Of Computer Networks

There are various types of computer networks categorized by their size.

• Personal Area Network(PAN)
• Local Area Network (LAN)
• Wide Area Network (WAN)
• Wireless Local Area Network (WLAN)
• Metropolitan Area Network (MAN)
• Storage Area Network (SAN)
• System-Area Network (SAN)
• Passive Optical Local Area Network (POLAN)
• Enterprise Private Network (EPN)
• Virtual Private Network (VPN)
• Home Area Network (HAN)
  
  

Personal Area Network(PAN)

It is the smallest and most basic type of computer network. The size of PAN varies from centimeters to 30 meters. PAN network can be classified into two types

• Wired PAN Network
• Wireless PAN Network

Examples of PAN are – USB, Computer, Bluetooth, etc.

Advantages Of PAN are-

• Less Expensive
• Confined to a small space area
• Links to multiple devices concurrently
  
  

Disadvantages Of PAN are-

• Limited area
• Slow Data Transmission
• Interference with radio signal
  
  

Local Area Network (LAN)

LAN can be defined as a cluster of computers connected at a single physical location such as an office, building, etc. It is the most common type of network used. A LAN can also be formed with two computers connected over a network. Hub, Switches, Cables, and Optical fibers are used to connect various computers and devices to a network.

Examples of LAN are networking in a home, school, college, office, etc.

Advantages Of LAN are- 

• High data transfer rate
• Ease of setup
• Centralized Data
• Low Cost
  
  

Disadvantages Of LAN are-

• Covers small area
• The cables and connectors get damaged easily
• Requires administrative time
  
  

Wide Area Network (WAN)

A WAN is a type of computer network that covers a large geographical area. WAN is also defined as the connection of several LANs linked together to cover an entire city or country. The WAN network is provided via several methods such as telephone lines, fiber optics cable, and also through satellite links.

Advantages Of WAN are- 

• Covers vast area
• Multiple users can share and access the internet at the same time
• High Bandwidth
  
  

Disadvantages Of WAN are- 

• High initial investment cost
• Hard to handle as the network is vast and complex.
• Less secure
  
  

Wireless Local Area Network (WLAN)

WLAN functions like WAN but without cables i.e, these are wireless. WLAN allows devices to connect wireless and it follows a standard called IEEE 802.11. WLAN connects laptops, smartphones, personal digital assistants, desktop computers, printers, etc. It is easy to install and use.

Advantages Of WLAN are-

• Economical to use as it has smaller access to an area 
• Easier to provide connectivity in areas where cable laying is not possible
• Easy to install as no cable layout is needed
  
  

Disadvantages Of WLAN are-  

• Covers a limited area
• Can interfere with other devices as it uses radio waves
• Decrease in data transfer rate with increase in devices connected
  
  

Metropolitan Area Network (MAN)

This type of network is created by linking existing LAN networks to cover a large geographical area. MAN is smaller than LAN but larger than WAN.

Examples of MAN are networking in government agencies, airports, libraries, etc.

Advantages Of MAN are-

• Offers Centralized data management
• Quick transfer of files
• Provides higher speed of internet as it uses fiber optics
  
  

Disadvantages Of MAN are-  

• Difficult to handle due to large network size
• Risk of hacking
• High installation cost as it requires fiber optics
  
  

Storage Area Network(SAN)

This network is good for small businesses. SAN network comprises various switches, storage devices, and storage elements that are interconnected with each other. SAN network does not depend upon LAN or WAN networks.

Advantages Of SAN are-

• Improvised Data Security
• Reduces LAN bandwidth problems
• Dynamic failover protection
  
  

Disadvantages Of SAN are-  

• Expensive
• High maintenance
• Complex in nature
  
  

System-Area Network (SAN)

SAN is a conglomeration of networks designed for high-speed interconnection in (server-server) mode. It uses fiber optics to establish this fast connection.

Examples of SAN are Fiber channels, etc.

Advantages Of SAN are-

• Can handle large volumes of data
• Ideal for high-level network performance
• Has high bandwidth
  
  

Disadvantages Of SAN are-  

• Hard to handle as the network is vast and complex.
• Complex in nature
• High initial cost
  
  

Passive Optical Local Area Network (POLAN)

POLAN functions in a similar way to LAN. It uses optical splitter instead of electrical powered switches to separate and collect optical signals and is based on point to multipoint architecture.

Examples of POLAN are networking in medium-size companies, hospitals, hotels, etc.

Advantages Of POLAN are-

• It is flexible
• Economical and Environment Friendly
• Low requirement of energy
  
  

Disadvantages Of POLAN are-

• Difficult to detect the failure in splitters
• Includes Expensive components
• Difficult in installation
  
  

Enterprise Private Network (EPN)

This is a type of private network mostly owned by businesses who want to connect their various branches to share computer resources.

Examples of EPN are communication between the head and remote offices, connecting various branches of a parent company, etc.

Advantages Of EPN are-

• Safe and secure network
• Helps in centralizing the IT resources
• Cost-effective for big companies
  
  

Disadvantages Of EPN are-

• High services fees
• Coverage limitation
• Difficult to set up
  
  

Virtual Private Network (VPN)

A VPN is a private network that connects remote users or sites using a public network. A VPN uses tunneling or virtual point-to-point connection technology to connect which creates a secure connection between the users or sites having the same IP address.

Advantages Of VPN are-

• Helps in creating a virtual IP address
• Bypasses Geo-Restrictions
• Increases Online Privacy
  
  

Disadvantages Of VPN are-

• Dropped Connections
• Data logging
• Slow connection speeds
  
  

Home Area Network (HAN)

HAN is used to share various computers or peripheral devices used in the same home. There is one device that acts as a centralized device for the function of Network Address Translation(NAT).

Examples of HAN are printers, game systems, tablets, WiFi, etc.

Advantages Of HAN are-

• Resource Sharing
• Security
• MultiUser
  
  

Disadvantages Of HAN are-

• Slow Connectivity
• Expensive
• High Security
  
  

Computer networks can be described based on their sizes and purpose. The most widely used computer networks are LAN, WAN, MAN, and PAN. We have covered here various types of networks with their advantages and disadvantages. Thanks for reading.

Kuldeep Rana

Kuldeep is the founder and lead author of ArtOfTesting. He is skilled in test automation, performance testing, big data, and CI-CD. He brings his decade of experience to his current role where he is dedicated to educating the QA professionals. You can connect with him on LinkedIn.

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