Protocols

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Protocols

A protocol is a set of rules that allow devices to communicate. There are a number of potocols you need to be familiar with.

TCP

TCP is short for transmission control protocol. It is used to break up data that is to be sent across the internet into small chunks called packets. It labels packets with senders and receivers IP addresses, total number of packets in the transmission and the number of this packet and uses this information to check for errors when the data is received at the other end and reassemble the file.

IP

IP is short for internet protocol. It is used to route packets from source to destination. It does this using network address tables that update the fastest way to each of the routers they are connected to every time a packet is sent. By consulting these tables packets are each sent the fastest way to the destination, though they may not all go the same way as the fastest route is always changing.

HTTP and HTTPS

HTTP is short for hyper text transfer protocol. It is the protocol used to request HTML web pages from a web server for viewing in a web browser.

HTTPS is short for hyper text transfer protocol secure. It serves the same purpose as HTTP but in addition it encrypts information before it is transmitted so if it were intercepted it could not be read. This is why it is used when sensitive details like banking login details are being transmitted. A padlock can be seen in the URL when using HTTPS.

FTP

FTP is short for file transfer protocol. It is used to transfer files between a client and a server on a network. FTP is commonly used to transfer web pages to a hosting server.

SMTP

SMTP is short for simple mail transfer protocol. It is responsible for sending emails you compose and send to your email server. It is also responsible for sending the email from your mail server to the recipient's mail server.

IMAP

IMAP is short for internet messaging access protocol. It is the protocol used to allow users to view email messages on the server as though they were on their local device. This includes being able to organise messages into groups, set reminders, store draft messages and more.

POP

POP is short for post office protocol. It is a legacy format for accessing emails rarely used anymore. When messages are accessed from the email server, they are downloaded to the device that accesses them and removed from the server. If you try to view the message from a different device later, it will not be there.

Layers

Layers refers to breaking up a protocol into smaller steps e.g. in the TCP/IP process data passes through 4 layers at either end of a transmission. The application layer encodes and decodes data. The transport layer breaks the data into chunks and reassembles it at the other end. The network layer adds the senders and receivers addresses to packets about to be sent and removes them from received packets. The link layer is responsible for routing the data from one computer to another.

By using a different protocol on the application layer, we are able to make use of the same transport methods for a variety of different purposes e.g. http, ftp and smtp

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