Computer Science GCES AQA
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Representing Algorithms Aqa4 主题
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Efficiency Of Algorithms Aqa1 主题
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Searching Algorithms Aqa3 主题
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Sorting Algorithms Aqa3 主题
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Data Types Aqa1 主题
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Programming Concepts Aqa5 主题
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Arithmetic Relational And Boolean Operations Aqa1 主题
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Data Structures Aqa3 主题
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String Manipulation Aqa1 主题
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Random Number Generation Aqa1 主题
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Structured Programming Aqa2 主题
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Robust And Secure Programming Aqa4 主题
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Number Bases Aqa2 主题
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Converting Between Number Bases Aqa3 主题
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Units Of Information Aqa9 主题
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Hardware And Software Aqa4 主题
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Boolean Logic Aqa3 主题
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Programming Languages And Translators Aqa2 主题
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Cpu Architecture Performance And Embedded Systems Aqa4 主题
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Memory Aqa2 主题
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Secondary Storage Aqa3 主题
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Fundamentals Of Computer Networks Aqa8 主题
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Fundamentals Of Cyber Security Aqa1 主题
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Methods Of Preventing Cyber Security Threats Aqa1 主题
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Relational Databases Aqa2 主题
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Ethical Legal And Environmental Impacts Aqa2 主题
The Concept Of Layers Aqa
Exam code:8525
The Concept of Layers
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Networks have lots of parts that must work together at the same time
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Different types of networks (e.g. LAN, WAN)
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Different ways networks are managed (operating models)
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The internet
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Wired and wireless connections
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Encryption (keeping data secure)
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Addressing (IP and MAC addresses)
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Protocols (rules for how devices communicate)
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Managing the complexity of networks is helped with the use of layers
What is a layer?
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A layer is a sub part of a more complex task
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Dividing network tasks into layers reduces the complexity and makes each layer more manageable
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An example of layers can be seen in the TCP/IP protocol which uses a 4-layer model known as a ‘stack‘
What are the advantages of layers?
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Layers are self-contained which makes managing, repairing and upgrading easier as each layer can be worked on independent of other layers
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Layers allow for focus on specific parts of a protocol without affecting other layers
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Promotes data exchange (interoperability) between hardware and software
Examiner Tips and Tricks
In the exam you are required to understand the concept of layers AND describe the main function of TCP/IP layers
TCP/IP Model
What is the TCP/IP model?
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The TCP/IP model is made up of two protocols (TCP & IP), containing 4 layers, that work together to package, address, transmit and receive data on a wide area network (Internet)
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There are four layers that make up the TCP/IP protocol stack:
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Application
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Transport
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Internet
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Link
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Different protocols operate on different layers
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Layer |
Function |
Protocols |
|---|---|---|
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Application |
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HTTP HTTPS FTP (Legacy) SMTP IMAP |
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Transport |
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TCP UDP (Legacy) |
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Internet |
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IP |
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Link |
|
|
Examiner Tips and Tricks
Key specification changes for AQA GCSE Computer Science (8525) – first exam 2027
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The “UDP (User Datagram Protocol)” is no longer a required protocol to study
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The “FTP (File Transfer Protocol)” is also no longer a required protocol
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You do not need to know alternative names for the “link layer” in the TCP/IP model, such as ‘network access layer’ or ‘network interface layer’
Worked Example
TCP/IP is a set of protocols based on layers.
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With regards to network protocols, define what is meant by a ‘layer’ [1]
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Describe one advantage of using layers to construct network protocols [2]
Answers
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Breaking up a complex task into more manageable sub tasks
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Self-contained
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…it allows different developers to concentrate on one aspect of the network
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A layer can be taken out and edited without affecting other layers…
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…it promotes interoperability between vendors and systems
Responses