Network Protocols (OCR GCSE Computer Science)

• Standards exist in computing to allow hardware and software to work together
• Standards outline the broad guidelines and protocols focus on specific procedures

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:
  • TCP/IP
  • HTTP & HTTPS
  • FTP
  • POP, IMAP & SMTP

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 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

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

• 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 POP?

• Post Office Protocol (POP) is a protocol for downloading emails to a device from an email server
• Once the email has been retrieved it is removed from the 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

Advantages & disadvantages of POP/IMAP

	Advantages	Disadvantages
POP	Frees up storage space on email servers Faster on slow connections	Only access emails from the device they're downloaded to Emails deleted on the server once downloaded
IMAP	View and manage emails from any device with internet access Changes made on one device are synchronised on all connected devices	Server storage space can limit amount of retained emails Requires internet access to view emails