network-models

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Client-server & peer-to-peer

A client-server network is when powerful and reliable ‘server’ computers control the network and ‘serve’ the clients with services such as files, email, web access, etc
Clients connect to the servers to access network services
In this setup, the server hosts, delivers and manages most of the resources and services to be consumed by the clients

Benefits	Drawbacks
Easier central management	Single point of failure – if the server goes down, services could be unavailable
Scalability: new clients can be added easily	It can be expensive to set up and maintain – often need dedicated teams of people to maintain them
Higher reliability as resources are managed centrally

A client-server network is typically used by larger organisations where centralised control is needed, and reliability and security are paramount

The choice between client-server and peer-to-peer depends on the specific needs and resources of the network in question
Security, cost, ease of setup, and maintenance requirements should be considered

This is the simplest type of network
In this setup, all computers in the network share equal responsibility, and there is no central server
All machines have equal status
Each machine is the responsibility of that machine’s user in terms of security, backup, etc.
Data is often spread around the network, with each user being responsible for their data

Benefits	Drawbacks
Easy to set up and less expensive than client-server as no administrative staff are needed	Lack of central control can lead to security issues and vulnerabilities
No dependency on a central server	Not suitable for large networks as it can have performance issues
Data can be shared directly between systems without the need for a central server

A peer-to-peer network is typically used in home networks, by small businesses, or for specific applications like file sharing

The Internet uses a client-server model.

Describe the role of clients and servers on the Internet [2]

Answer

Web pages/files are saved on servers [1 mark]
Clients send requests to the web servers [1 mark]
Web servers process the requests [1 mark]
- …and return the results to the client [1 mark]
- the client displays the results to the user [1 mark]

A thin client relies on a permanent connection to a server to function
Can be hardware (a device) or software (an app or program)
Depends on the processing power of another computer or server
Cannot function without being connected to a networked computer or server
The server can be part of a LAN (local area network) or a WAN (wide area network)
Examples of thin-clients include:
- Cloud-based apps like Google Docs or Microsoft 365
- Remote desktop software (e.g. Chrome Remote Desktop, Citrix)
- Supermarket POS systems connected to a central server for prices, stock, and payments

Works independently without needing constant connection to a server
Can be a hardware device or software installed on a local machine
Uses the processing power of its own device to run applications
May connect to a network for updates or data sharing, but can function offline
Often used where performance, speed or offline access is important
Examples of thick-clients include:
- Installed software like Adobe Photoshop or Microsoft Word
- Standalone games installed and played on a PC or console
- School or office PCs running full applications locally
- Laptops that can run applications without an internet connection

Feature	Thin-client	Thick-client
Dependence on server	Needs a permanent connection to a server to function	Can work independently of a server
Processing power	Uses the server’s processing power	Uses its own local processing power
Functionality when offline	Does not work without a connection	Can function offline
Examples	Google Docs, Microsoft 365, Remote Desktop, supermarket POS systems	Microsoft Word, Adobe Photoshop, standalone games, school laptops
Best for	Centralised control, low-cost devices, shared environments	Performance, flexibility, offline access
Network type	Part of a LAN or WAN	May connect to a network, but not reliant on it