Computer Science AS CIE
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data-representation as5 主题
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multimedia as3 主题
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compression as2 主题
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networks-and-the-internet as11 主题
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computers-and-components as5 主题
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logic-gates-and-logic-circuits as2 主题
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central-processing-unit-cpu-architecture as6 主题
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assembly-language- as4 主题
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bit-manipulation as1 主题
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operating-systems as3 主题
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language-translators as2 主题
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data-security as3 主题
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data-integrity as1 主题
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ethics-and-ownership as3 主题
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database-concepts as3 主题
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database-management-systems-dbms- as1 主题
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data-definition-language-ddl-and-data-manipulation-language-dml as1 主题
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computational-thinking-skills as1 主题
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algorithms as4 主题
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data-types-and-records as2 主题
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arrays as2 主题
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files as1 主题
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introduction-to-abstract-data-types-adt as1 主题
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programming-basics as1 主题
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constructs as2 主题
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structured-programming as1 主题
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program-development-life-cycle as1 主题
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program-design- as2 主题
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program-testing-and-maintenance as3 主题
network-models- as
Exam code:9618
Client-server & peer-to-peer
What is a client-server network?
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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
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Clients connect to the servers to access network services
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In this setup, the server hosts, delivers and manages most of the resources and services to be consumed by the clients
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Benefits |
Drawbacks |
|---|---|
|
Easier central management |
Single point of failure – if the server goes down, services could be unavailable |
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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 |
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Higher reliability as resources are managed centrally |
|
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A client-server network is typically used by larger organisations where centralised control is needed, and reliability and security are paramount

When to use a client-server network
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The choice between client-server and peer-to-peer depends on the specific needs and resources of the network in question
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Security, cost, ease of setup, and maintenance requirements should be considered
Peer-to-peer
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This is the simplest type of network
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In this setup, all computers in the network share equal responsibility, and there is no central server
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All machines have equal status
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Each machine is the responsibility of that machine’s user in terms of security, backup, etc.
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Data is often spread around the network, with each user being responsible for their data
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Benefits |
Drawbacks |
|---|---|
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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 |
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No dependency on a central server |
Not suitable for large networks as it can have performance issues |
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Data can be shared directly between systems without the need for a central server |
|
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A peer-to-peer network is typically used in home networks, by small businesses, or for specific applications like file sharing

Worked Example
The Internet uses a client-server model.
Describe the role of clients and servers on the Internet [2]
Answer
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Web pages/files are saved on servers [1 mark]
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Clients send requests to the web servers [1 mark]
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Web servers process the requests [1 mark]
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…and return the results to the client [1 mark]
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the client displays the results to the user [1 mark]
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Thin-client & thick-client
What is a thin-client?
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A thin client relies on a permanent connection to a server to function
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Can be hardware (a device) or software (an app or program)
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Depends on the processing power of another computer or server
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Cannot function without being connected to a networked computer or server
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The server can be part of a LAN (local area network) or a WAN (wide area network)
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Examples of thin-clients include:
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Cloud-based apps like Google Docs or Microsoft 365
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Remote desktop software (e.g. Chrome Remote Desktop, Citrix)
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Supermarket POS systems connected to a central server for prices, stock, and payments
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Thick-client
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Works independently without needing constant connection to a server
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Can be a hardware device or software installed on a local machine
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Uses the processing power of its own device to run applications
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May connect to a network for updates or data sharing, but can function offline
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Often used where performance, speed or offline access is important
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Examples of thick-clients include:
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Installed software like Adobe Photoshop or Microsoft Word
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Standalone games installed and played on a PC or console
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School or office PCs running full applications locally
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Laptops that can run applications without an internet connection
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Feature |
Thin-client |
Thick-client |
|---|---|---|
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Dependence on server |
Needs a permanent connection to a server to function |
Can work independently of a server |
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Processing power |
Uses the server’s processing power |
Uses its own local processing power |
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Functionality when offline |
Does not work without a connection |
Can function offline |
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Examples |
Google Docs, Microsoft 365, Remote Desktop, supermarket POS systems |
Microsoft Word, Adobe Photoshop, standalone games, school laptops |
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Best for |
Centralised control, low-cost devices, shared environments |
Performance, flexibility, offline access |
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Network type |
Part of a LAN or WAN |
May connect to a network, but not reliant on it |
Responses