What happens at the application layer?

The application layer is where network applications such as web browsers and email programs operate. The application layer turns what the user asks for into data to send.

Which protocols operate at the application layer?

HTTP, HTTPS, SMTP, IMAP and FTP operate at the application layer.

What does the transport layer do?

The transport layer sets up the communication between the sending and receiving computers. The two computers agree how data will be exchanged, such as how large each packet is.

Which protocols operate at the transport layer?

TCP and UDP operate at the transport layer.

AQA GCSE Computer Science 8525

Algorithms

Topic overview Algorithms, decomposition and abstraction Pseudo-code, flowcharts and trace tables Efficiency of algorithms Linear search and binary search Bubble sort and merge sort

Programming

Topic overview Data types Variables, constants and assignment Sequence, selection and iteration Arithmetic, relational and Boolean operators Arrays and records Input, output, string handling and random numbers Subroutines and structured programming Validation, authentication and testing

Data Representation

Topic overview Number bases and why hexadecimal is used Converting between binary, decimal and hexadecimal Units of information: bits, bytes and prefixes Binary addition and binary shifts Character encoding: ASCII and Unicode Pixels, bitmaps and colour depth Bitmap image file size calculations Digital sound: sampling rate and sample resolution Data compression: Huffman coding and run-length encoding

Computer Systems

Topic overview Hardware, software and the operating system Logic gates, truth tables and Boolean expressions Programming languages and translators The CPU and the fetch-execute cycle Types of memory and embedded systems Secondary storage and cloud storage

Computer Networks

Topic overview Network types and topologies Wired and wireless networks Network protocols The TCP/IP model and its layers Network security methods

Cyber Security

Topic overview Cyber security, common threats and penetration testing Social engineering: blagging, phishing and shouldering Malware: viruses, trojans and spyware Methods to detect and prevent cyber security threats

Relational Databases and SQL

Topic overview Relational databases and keys SQL SELECT queries SQL INSERT, UPDATE and DELETE

Ethical, Legal and Environmental Impacts of Digital Technology

Topic overview Ethical issues in digital technology Legal issues, privacy and surveillance Environmental impacts of digital technology

Computer Networks

The TCP/IP model and its layers

3 things to know
Paper 2

Overview

The application, transport, internet and link layers, the protocols at each, the network interface card, and how data moves down and up the layers between two computers.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What happens to data at the internet layer and the link layer of the TCP/IP model?

Key term

Name the four layers of the TCP/IP model, from top to bottom.

Key term

Why is network communication split into layers?

Questions from this subtopic

Each one with the model answer underneath.

1
Name the four layers of the TCP/IP model, from top to bottom.
Model answer
The four layers are application, transport, internet and link. The application layer is at the top.
2
Why is network communication split into layers?
Model answer
Each layer has its own job and only deals with the layers directly above and below it. One layer can be changed without affecting the others.
3
What happens at the application layer?
Model answer
The application layer is where network applications such as web browsers and email programs operate. The application layer turns what the user asks for into data to send.
4
Which protocols operate at the application layer?
Model answer
HTTP, HTTPS, SMTP, IMAP and FTP operate at the application layer.
5
What does the transport layer do?
Model answer
The transport layer sets up the communication between the sending and receiving computers. The two computers agree how data will be exchanged, such as how large each packet is.
6
Which protocols operate at the transport layer?
Model answer
TCP and UDP operate at the transport layer.

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