How does the internet work?
The Blog you are reading now traveled thousands of miles from a Google
Data Center to reach you.
Let's learn how the internet works
by getting to understand the details of this data's incredible journey.
The
data center which can be thousands of miles away from you has your blog
article stored inside it. how does this data reach your mobile phone or a
laptop?
An easy way to achieve this goal would be with use of
satellites. From the data center, a signal could be sent to the satellite via
an antenna, and then from the satellite a signal could be sent to your mobile
phone via another antenna near to you.
However, this way of
transmitting signals is not a good idea. Let's see why The
satellite is parked nearly 22,000 miles above the earth's
equator, so in order for the data transmission to be successful, the data
would have to travel a total distance of 44,000 miles. Such a long
distance of travel causes a significant delay in receiving the signal. More
specifically it causes huge latency which is unacceptable for most internet
applications. so if this video does not reach you via a satellite then how
does it actually get to you?
Well it is done with the help of a complicated network of optical fiber
cables, which connect between the data center and your device. Your phone
could be connected to the internet via cellular data or any
Wi-Fi router, but ultimately at some point your phone will be connected to this network
of optical fiber cables We saw at the beginning that the video you are
currently watching is stored inside a data center. To be more specific, it is
stored in a solid-state device within the data center. This SSD acts as the internal memory of a server. The server is simply a powerful
computer whose job is to provide you the video, article or other stored
content when you request it. Now the challenge is how to transfer the data
stored in the data center specifically to your device via the complex network
of optical fiber cables.
Let's see how this is done. Before
proceeding further we should first understand an important concept which is
the concept of an IP address. Every device that is connected to the Internet
whether it is a server a computer or a mobile phone is identified uniquely by
a string of numbers known as an IP address. You can consider the IP address
similar to your home address that is the address, that uniquely identifies
your home. Any letter sent to you reaches you precisely because of your home
address. Similarly in the internet world an IP address acts as a shipping
address through which all information reaches its destination. Your internet
service provider will decide the IP address of your device and you are able to
see what IP address your ISP has given to your mobile phone or laptop. The
server in the data center also has an IP address. The server stores a website
so you can access any website just by knowing the server's IP address.
However, it is difficult for a person to remember so many IP addresses.
So
to solve this problem domain names like
kumaratuljaiswal.in, hackingtruth.in, udemy.com, youtube.com, facebook.com etc are used which
correspond to IP addresses which are easier for us to remember
than the long sequence of numbers Another thing to notice here is that a
server has the capability of storing several websites and if the server
consists of multiple websites all the websites cannot be accessed with the
server's IP address.
In such cases additional pieces of
information, host headers are used to uniquely identify the website. However,
for the giant web sites like Facebook.com or YouTube.com the entire data
center infrastructure will be dedicated to the storage of the particular
website. To access the internet we always use domain names instead of the
complex IP address numbers.
From where does the internet get
IP addresses corresponding to our domain name requests. Well, for this purpose
the internet uses a huge phone book known as DNS. If you know a person's name, but don't know their telephone number you can
simply look it up in a phone book.
The
DNS server provides the same service to the internet. Your
internet service provider or other organizations can manage the DNS server.
Let's have a recap of the whole operation. You enter the domain name, the
browser sends a request to the DNS server to get the corresponding IP address.
After getting the IP address, your browser simply forwards the request to the
data center, more specifically to the respective server.
Once the
server gets a request to access a particular website the data flow starts. The
data is transferred in digital format via optical fiber cables, more
specifically in the form of light pulses. These light pulses sometimes have to
travel thousands of miles via the optical fiber cable to reach their
destination.
During their journey they often have to go through
tough terrains such as hilly areas or under the sea. There are a few global
companies who lay and maintain these optical cable networks. These visuals
show how the laying of optical fiber cables is done with the help of a ship. A
plow is dropped deep into the sea from the ship, and this plow creates a
trench on the seabed and to which places the optical fiber cable.
In
fact, this complex optical cable network is the backbone of the Internet.
These optical fiber cables carrying the light are stretched across the seabed
to your doorstep where they are connected to a router. The router converts
these light signals to electrical signals. An Ethernet cable is then used to
transmit the electrical signals to your laptop.
However if
you are accessing the Internet using cellular data, from the optical cable the
signal has to be sent to a cell tower and from the cell tower the signal
reaches your cell phone in the form of electromagnetic waves. Since the
Internet is a global network it has become important to have an organization
to manage things like IP address assignment, domain name registration etc this
is all managed by an institution called ICANN located in the USA. One
amazing thing about the internet is its efficiency in transmitting data when
compared with cellular and landline communication technologies. This video you
are watching from the Google Data Center is sent to you in the form of a huge
collection of zeros and ones.
What makes the data transfer in the
internet efficient is the way in which these zeros and ones are chopped up
into small chunks known as packets and transmitted. Let's assume these streams
of zeros and ones are divided into different packets by the server where each
packet consists of six bits.
Along with the bits of the video each
packet also consists of the sequence number and the IP addresses of the server
and your phone. With this information the packets are routed towards your
phone. It's not necessary that all packets are routed through the same path
and each packet independently takes the best route available at that time.
Upon reaching your phone the packets are reassembled according to their
sequence number. If it is the case that any packets fail to reach your phone
and acknowledgement is sent from your phone to resend the lost packets. Now
compare this with a postal network with a good infrastructure, but the customers
do not follow the basic rules regarding the destination addresses. In this
scenario letters won't be able to reach the correct destination.
Similarly
in the internet we use something called protocols for the management of this
complex flow of data packets. The protocols set the rules for
data packet conversion, attachment of the source and destination addresses to
each packet and the rules for routers etc for different applications the
protocols used are different. We hope this video has given you a good
understanding about how the internet works, more specifically about the
amazing journey of data packets from the data center to your mobile phone.
Disclaimer
All tutorials are for informational and educational purposes only and have
been made using our own routers, servers, websites and other vulnerable free
resources. we do not contain any illegal activity. We believe that ethical
hacking, information security and cyber security should be familiar subjects
to anyone using digital information and computers.
Hacking Truth is
against misuse of the information and we strongly suggest against it. Please
regard the word hacking as ethical hacking or penetration testing every time
this word is used. We do not promote, encourage, support or excite any illegal
activity or hacking.
- Hacking Truth by Kumar
Atul Jaiswal
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