When you open a web page, all sorts of things will need to be done in the background before you get your shiny website on your screen.
We will see now what is happening in the networking system to make that possible.
TCP/IP protocol is what makes sending and receiving most of the data across the Internet possible. But how data packets know how to find us and how we know how to find the IP addresses of the web servers where these pages are saved?
Data will maybe not even take the same route in each direction. It can happen that when we send something, a request to the server, the packets will flow through one route and the server response towards our computer will take some other route.
The Internet is the biggest computer networking system. It knows in every moment how to find the best route to some device connected anywhere in-between all his nodes.
But how is this data transferred across the wires, fibres and air?
Data is divided into small packets. Every time we send a request towards a server, our request must firstly be divided into packets, most of the same size. Each of those packets needs an IP address of the destination to be written on it so that he can be routed through the network.
In order to find out what is the destination IP address of the server – (remember that we are typing an URL into the browser, usually we are not typing IP address into it) – your computer, before sending out all those packets, will contact public DNS server – domain name server, that will have the information about IP address to which packets must be forwarded in order to get to your URL-linked page.
Public DNS servers are set up into a hierarchical system that keeps the knowledge of IP addresses for all URLs (domain names) that are registered on the Internet. With this database, DNS is able to translate our request for the web page URL into the IP address of the server on which the web page is stored.
So, when you open your web browser on your computer and type in the URL of this page howdoesinternetwork.com, the computer must connect to the server where this page is stored and download this page to your computer in order for you to see it.
Your computer knows the IP address of DNS server because you are manually configuring this on into your Network Card NIC or it will get configured by your DHCP server which is at your home your Internet router.
Computer DNS request goes through the Internet and at some point hits the DNS – domain name server who will look in his huge database and match the domain name you’ve entered with the IP address of the proper server. If the DNS server does not find a match, it will forward the request to next DNS server who maybe has more information. Not all DNS servers have all the data about all the domain names and they addresses.
When the server is found and the request has come to it, he will respond by sending the requested files in a series of packets.
Packets are files divided into small pieces that range between 1,000 and 1,500 bytes. Packets have some extra data called headers in the beginning and footers at the end and that data tell computers what’s in the packet and how the information can be put together with other packets to recreate an entire file that has been sent.
Each packet travels through the Internet into your computer. Packets don’t necessarily all take the same path, they will usually travel with the path of least resistance, which is the best path in that moment. I fact, that is the most powerful feature of the Internet. Packets can travel with different routes and in this way avoid congested routes and come to their destination even when an entire part of the Internet is down.
In the case of different types of files, the way that the network is making communication work is basically the same. VoIP calls, e-mails and other different files are also divided into packets and sent through the network to be recreated in the other end with the information in the header.