Networks (OCR A Level Computer Science)

Revision Note

Neil Southin

Written by: Neil Southin

Reviewed by: James Woodhouse

Networks

What is a Network?

  • A network is a set of interconnected devices (such as computers, printers, and servers) designed to share resources, exchange data and communicate with each other

  • The main purposes of a network are to enable data sharing, resource sharing, communication, and collaboration

Purpose & importance of protocols

  • Network protocols  define the rules and formats that devices must follow to communicate with each other over the network

  • They ensure successful and secure data transmission, and help maintain order and efficiency in communications

  • Examples of protocols include HTTP, FTP, TCP/IP, and SMTP, among others

Understanding the term "standard"

  • A standard in a network or any data transfer situation refers to a set of guidelines or frameworks that govern how a task should be performed or how a product should function

  • Standards ensure compatibility, interoperability, and consistency across different devices and software

Purpose & need for standards in a network

  • Standards enable different network devices, regardless of their manufacturer or model, to work together seamlessly

  • They ensure that data can be correctly interpreted and processed by the receiving device, regardless of where or how it was sent

  • Standards support network expansion and the integration of new technologies without disrupting existing operations

  • They foster innovation and competition by providing a common ground for all manufacturers and developers

Common Internet Protocols


Protocol


Notes

HTTP
(HyperText Transfer Protocol)

Primary protocol for transferring web content (text, images, video)
Works as a request-response protocol in a client-server computing model

HTTPS
(HTTP Secure)

A version of HTTP, but with encryption for security
Used for secure transactions like online banking and shopping

SMTP
(Simple Mail Transfer Protocol)

The standard for sending email messages between servers
It is also used to send emails from a client to a server for further forwarding

FTP
(File Transfer Protocol)

Used for transferring files from one host to another over a network
Provides authentication (username and password) and can manage file directories

ARP
(Address Resolution Protocol)

Translates IP addresses into MAC (Media Access Control) addresses
This ensures that data packets reach the correct device on a network

TCP
(Transmission Control Protocol)

Part of the main suite of protocols used in the Internet Protocol Suite
Provides reliable, ordered, and error-checked delivery of a stream of packets

UDP
(User Datagram Protocol)

A simpler message-based connectionless protocol
UDP does not guarantee delivery by disregarding order and error-checking, making it faster

IP 
(Internet Protocol)

Functions mainly by addressing and routing packets of data from the source to the target device

Worked Example

The internet can be considered an example of a WAN.
The internet uses a set of protocols referred to as the TCP/IP stack. The TCP/IP stack consists of four different layers, each with its own set of protocols.

Explain why protocols are important on a network                        

2 marks

How to answer this question:

  • You need to know what network protocols are and why they are important for network communication:

    • They allow us to communicate over a network by ensuring that all communicating parties use the same rules and standards

    • Whatever data or signals are sent need to be understood commonly by both the sender and the receiver

Answer:

Example answer that would get full marks:

Protocols are rules that must be followed to allow communication over a network. They ensure that all devices follow the same rules and standards so that they interpret data and signals in the same way.

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Neil Southin

Author: Neil Southin

Expertise: Computer Science

Neil has been a passionate Computing teacher for nearly 20 years, teaching Computing and ICT in a large Sixth Form College.

James Woodhouse

Author: James Woodhouse

Expertise: Computer Science

James graduated from the University of Sunderland with a degree in ICT and Computing education. He has over 14 years of experience both teaching and leading in Computer Science, specialising in teaching GCSE and A-level. James has held various leadership roles, including Head of Computer Science and coordinator positions for Key Stage 3 and Key Stage 4. James has a keen interest in networking security and technologies aimed at preventing security breaches.