The Internet
Contents
What is the Internet
The Internet is an international Wide Area Network. It connects computers and networks over a large area.
The Internet originates with the U.S. government's Advanced Research Projects Agency and was used for governmental and academic communication purposes. At this stage in the development it was used to send files and emails. After the issues of connecting packet switched networks was solved, the internet took a more recognizable form. By 1983 TCP/IP protocol was created and today's internet was essentially formed.
The term 'The Internet' was adopted in 1995.
How is the Internet connected
Router
A Router receives packets from a host or router and uses the destination IP address that they contain to pass on the packets to another host or router.
It would be impractical to connect hosts to other hosts, which is the main reason as to why we use routers. So that many hosts can connect to the router and then the router can connect to other networks.
Gateway
A Gateway is basically Donald Trump. It controls the wall between two different systems, for example on your home router to connect from your devices to the Internet. However, unlike the Donald, Gateways can translate. They translate the current protocols for the new system to understand. This allows two different systems with different protocols to be connected. Without this, data would be kept outside the border and could not communicate across it - welcome to Trump's America.
How is data transmitted
Packet Switching
Instead of having a circuit between the sender and receiver, the data transmitted is broken into small chunks (packets). Each packet is sent separately over a network on which other similar communications are happening simultaneously. The data is reconstructed on arrival.
Circuit Switching
This creates a circuit between the sender and receiver, they are connected for the duration of the transmission. This is essentially how the telephone system works. However this means that once connected neither the sender or receiver can connect or transmit to another location. It also means that if the connection is dropped then the transmission will also cease.
The End to End Principle
The devices that are communicating should be the endpoints of the communication with no external input. The Internet serves as a medium to carry traffic between them but makes no changes the data involved. Therefore the transmitting devices control every aspect of the transmission, allowing security (through encryption) and the detection of errors, which maintains the integrity of transmitted data.
Using this principle allows the Internet to easily grow because there is no direct control over the number of endpoints.
URL
The Uniform Resource Locator is the standard address used to find a page, Web server or other device on the Web or Internet.
It specifies: How to access the server, ie which protocol to use Which server to access, ie the address if server What is to be accessed on the server, ie the path on the addressed server.
This was invented so that users could use a memorable name to refer to a network and a host on that network. Often the term 'Domain Name' is used instead of the correct term 'Full Qualified Domain Name' (FQDN). The domain name identifies one or more IP addresses. For example, the domain name "Microsoft.com" represents about a dozen IP addresses.
The DNS system is a hierarchy. A Domain Name Server accepts a Domain Name and returns the IP address associated with this Domain Name.
Domain Name
IP Address
Class 1
Class 2
Class 3
Domain Name Server
Internet Registrar
An organization which is capable of providing and controlling the domain of an URL is known as a registrar. They allow for the reservation of specific web addresses for anybody who wishes to purchase it, a vast majority of which are to be repaid annually or else be open to the public again.
Different domains have different costs and requirements depending on what they are, with the best examples being country-specific top-level domains such as .uk or .us
Domains that are created by and for governmental and military purposes are typically restricted from the public or are made invisible to the public altogether.
Internet Registries
An Internet Registry holds registered domain names, according to which ones are currently in use. The registry will allow users accessing the domain name to access the linked IP address and thus the intended website.
