OAI - Operation and Abstractions of the Internet Lesson

Operation and Abstractions of the Internet

What happens when we type an address into the URL bar? It takes us to a listing for that URL. We click on the link and view our webpage. Well, a little more than that is actually happening. Remember an abstraction is hidden details about a complex system so we don't have to worry about details. There are many abstracted layers that make the Internet function.      

When you type google.com in the URL bar, you are typing the Domain Name for the website.      

Data Flow on the Internet Video

How is a Domain Name abstracted?

A Domain Name System is part of the Internet Protocol TCP/IP. Domain names reside on special database servers called Domain Name Servers (DNS Servers).  DNS distributes the responsibility of assigning domain names and mapping those names to Internet Protocol (IP) addresses. The IP Protocol uses IP addresses to identify individual devices connected to the internet. An IP address is a unique numerical address assigned to anything connected to the Internet.   The IP address is made up of four bytes of information totaling 32 bits as shown below. The human readable decimal form is converted to binary for the computer to read.  

There are approximately four billion IP addresses using the IPv4 address system. It may sound like enough but remember every device connected to the internet must have an IP address. This includes computers, gaming systems, smartphones, and tablets to name a few. With all the devices connected to the Internet, a new IPv6 addressing system was developed. It will support up to 340,282,366,920,938,463,463,374,607,431,768,211,456 different addresses using a 128-bit system. The domain name system allows the Internet to scale. IPv6 will allow more devices the ability to connect to the Internet.  

The IP address is used to identify the client computer and the host computer. A client computer is an individual computer that accesses the information and programs stored on a server as part of a network. The system that contains the data is called the host.  

 The information sent and received through the Internet is broken into a certain size in bytes called packets, a unit of data that is routed between an origin and a destination on the Internet. Each packet carries the sender's IP address (source), the receivers address (destination), the message, how many packets it has been broken into, the number of that particular packet, and other identifiable information. A typical packet contains perhaps 1,000 or 1,500 bytes. Networks that ship data around in small packets are called packet switched networks.

A router, a device that forwards data packets along networks, is used to send the packet to its destination.  Each packet may take a different route depending on the traffic load on the network.  

Another protocol called TCP (Transmission Control Protocol) is a connection-oriented Transport layer protocol. It is responsible for reliably delivering a packet on the network. If something happens and the packet doesn't get delivered, TCP resends the packet. The connection is not closed until all packets have been successfully delivered or there is an unrecoverable error.

Network Internet Protocol Video

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