Network Protocols (AQA GCSE Computer Science)
Revision Note
Network Protocols
What is a protocol?
A protocol is a set of rules that govern communication on a network
There are protocols for different purposes, such as:
Ethernet & Wi-Fi
TCP/IP & UDP
HTTP & HTTPS
FTP
IMAP & SMTP
Ethernet & Wi-Fi
What is Ethernet
Ethernet is a family of related protocols used in data communication/transfer on a wired local area network (LAN)
What is Wi-Fi?
Wi-Fi is a family of related protocols used in data communication/transfer on a wireless local area network (LAN)
Wi-Fi is a trademark, the generic term used to describe networks that make use of Wi-Fi is wireless local area network (WLAN)
Examiner Tip
Key point to remember, Wi-Fi is a brand name! Any local area network that uses wireless technology to connect devices is known as a wireless local area network (WLAN)
TCP/IP & UDP
What is TCP/IP?
TCP/IP is two protocols, transmission control protocol (TCP) and internet protocol (IP) that combined allow communication over the internet (WAN)
TCP is responsible for making sure communication between two routers is error free
IP is responsible for making sure data is delivered to the right device on a wide area network (WAN)
What is UDP?
User Datagram Protocol (UDP) is an alternative to TCP to send data across a wide area network (WAN)
UDP is faster than TCP but less secure and does not guarantee error free transmission
UDP is an open, two way communication used in activities where some data loss is acceptable, for example online gaming
TCP is much more reliable than UDP
HTTP & HTTPS
What is HTTP & HTTPS?
Hypertext Transfer Protocol (HTTP) allows communication between clients and servers for website viewing
HTTP allows clients to receive data from the sever (fetching a webpage) and send data to the server (submitting a form, uploading a file)
HTTPS works in the same way as HTTP but with an added layer of security. All data sent and received using HTTPS is encrypted
HTTPS is used to protect sensitive information such as passwords, financial information and personal data
FTP
What is FTP?
File Transfer Protocol (FTP) allows sending and receiving files between computers
Uploading and downloading files to/from a web server is often completed using FTP
FTP offers greater efficiency and support for bulk transfers and large files such as resuming interrupted transfers
FTP clients are software applications that use the FTP protocol to make the process easier for users
IMAP & SMTP
A family of protocols that handle sending and receiving of email across the internet (WAN)
What is SMTP?
Simple Mail Transfer Protocol (SMTP) is a protocol that allows communication between an email sender and the email server, and between different email servers using the internet
In the diagram above, SMTP is used to transfer the senders email to their email providers server and SMTP is used to transfer the email to the recipients email server
What is IMAP?
Internet Message Access Protocol (IMAP) is a protocol for downloading emails to a device from an email server
Once the email has been retrieved, a copy is retained on the mail server
Worked Example
Explain the purpose of the HTTPS protocol [2]
Answer
sending/receiving web pages
using an encrypted connection // provides an encrypted version of HTTP
more secure web transactions
authentication of the website being visited
encryption of the data between the server and the client
reduces likelihood of man-in-the-middle attacks
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