1.3.3 Networks

Interconnected devices Enables data and resource sharing and communication

A set of rules for communication between devices over a network

Ensures successful and secure transfer of data over a network

Hypertext Transfer Protocol Used for web page rendering

Hypertext Transfer Protocol Secure An encrypted form of HTTP

Transmission Control Protocol / Internet Protocol Networking protocol used in routing packets through networks A stack of networking protocols that work together to pass packets for communication

Post office protocol Mailing protocol used for email access

Internet Message Access Protocol Mailing protocols used for email access

IMAP is ideal for accessing emails across multiple devices, syncronising changes in real time and storing emails on a server POP3 is ideal for downloading emails to a single device and is better for offline access and limited server storage

File transfer protocol Used for the transmission of files over networks

A network of networks which allows computers to communicate from anywhere in the world. Using large international backbone cables that pass underwater to link continents.

The way network protocols are divided into layers Each layer has a specific function

Increases modularity by breaking complex process into layers Can use different systems and allow them to work together Updates are easier

Application Transport Network Link

Interacts directly with software Prepares data for transmission by converting it into the correct format (encapsulation)

Receives data from the application layer Responsible for end to end communication Breaks data into packets Assigns port number and header (containing the packet number)

The total number of packets the original data was split into and the port number being used for communication

Receives packet from transport layer Routes each packet across the network using the IP address

Used to identify computers on a WAN like the internet

Prepares packets for transmission over the physical network Translates packets into electrical, optical or wireless signals Translates received packets back to digital ones

The data A header (source and destination) A footer (shows end of packet)

Translates human-readable domain names to the IP addresses Used to name and organise internet resources Easier to remember than IP addresses

The MAC address is removed by the link layer The IP addresses are removed by the network layer Transport layer removes port numbers and reassembles the packets Application layer presents data in its desired form

A unique 12 character alphanumeric identifier assigned to a devices NIC Used to identify it on a network For devices on the same network, the MAC address in the link layer will be the recipients computer For devices on other networks, the MAC address in the link layer will be of the router