Network protocols

HTTP

An insecure protocol used between a browser and web server. Hypertext Transfer Protocol transmits HTML web pages from web server to client

HTTPS

Secure version of HTTP, the traffic is encrypted between the browser and the web server for security. Now fairly standard

TCP

This sets up and maintains a reliable connection between two computers, e.g. client's browser and web server

IP

This protocol describes how to route packets of data around networks. It's used by routers and switches to direct packets

IMAP

Alternative email protocol to POP, the client can read emails but they stay on the server.

FTP

Protocol for transferring files to and from a file server.

SMTP

Rules for sending emails from client to server, and then server to server.

POP

Used by client to download emails from mail server. Post Office Protocol is older and less useful than IMAP

Wi-Fi

Wireless connection standards are known by this 4-letter acronym, this describes how wireless devices connect

Ethernet

The protocols used at the lowest layer of a network, describing the rules for connecting hardware and cables

Protocol

A set of agreed rules which allow two devices to communicate. SMTP, HTTPS and TCP are all examples

Bluetooth

Wireless PAN technology that transmits signals over short distances between smartphones, computers and other devices e.g. headsets and fitness trackers

Encryption

Converting readable data into unreadable characters to prevent unauthorized access. Authorised recipients can reverse the process with the key. HTTPS uses it

IP address

Number that uniquely identifies each device connected to a network. IPv4 format is 4 bytes, IPv6 uses 16 bytes for more addresses.

IPv4

A version of the IP protocol that uses 32-bit (4-byte) addresses such as 104.16.15.221. There are only around 4 billion possible IPv4 addresses and we are running out, so IPv6 is now preferred

IPv6

The latest version of the IP protocol, it uses 128 bits (16 bytes) for every address so they will never run out. Addresses are shown as 4 pairs of hex bytes like this: a490::65d8:4282:7f30

128

Number of bits in an IPv6 address

32

Number of bits in an IPv4 address

4 billion

Approximate number of IPv4 addresses, because IPv4 is limited to 32 bits giving 2^32 possible values

Standard

Published document that says how hardware or software must behave or interact, e.g. the Wi-Fi rules 802.11, the HTML structure and the cable types Cat 5e and Cat 6.

Layer

A level in the protocol stack. Protocols in each of these perform related services, and each must talk to the one above and below.

TCP/IP

The 4-layer "protocol stack" that makes the internet work. Includes Ethernet, IP, TCP and HTTP which all have a role to play in delivering a services over the web