The document explains the fundamentals of the internet, including the definitions of key terms like domain names and IP addresses, and the process by which data is sent over networks. It details how data packets are created, routed, and reassembled at their destination, emphasizing the role of routers and the efficiency of packet switching. Advantages and disadvantages of packet switching versus circuit switching are also discussed.

1. mashable.com

2. What is the Internet?
a global computer network providing a
variety of information and communication
facilities, consisting of interconnected
networks using standardized
communication protocols.
Oxford Dictionary Definition

4. Domain Name - the part of a network
address which identifies it as belonging to
a particular domain.
Oxford Dictionary Definition
IP Address - a unique string of numbers
separated by full stops that identifies each
computer using the Internet Protocol to
communicate over a network.
Oxford Dictionary Definition

5. The IP address identifies a particular
device/network, which means that data
can then be exchanged with it. However
the IP address consists of number, and
addresses like 198.546.0.32 are not easy for
humans like us to remember.
The majority of the internet, the world wide
web, which we are all familiar with, is
concerned with us users making use of such
websites, with one of the most used being
www.google.com . These are user-friendly
labels known as domain names or a URL. A
scheme has been developed that can convert
this domain name into an underlying IP
address.
https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAYQjB0&url=http%
3A%2F%2Fwww.clipartpanda.com%2Fcategories%2Fcomputer-clipart-for-kids&
ei=7AaDVKLJFMf4UoPKgsgP&bvm=bv.80642063,d.d24&psig=AFQjCNGmlZRMAB1yKo6BymrOGbCmC5SOtg&ust=14
17959531187397

7. 1.You enter a
domain name
into the browser

8. 2. Your browser makes contact
with the DNS server. This server
contains a database that matches
the domain name to its
registered IP address. THE DNS
sends this information back to
the computer/device.

9. 3. The computer
attaches this IP
address to the data
packet to be sent

10. 4. The data packet
travels over the
internet to its
destination

11. 5. The end server
send back the
requested data.

12. https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAYQjB0&url=
http%3A%2F%2Fchrezsoft.blogspot.com%2F2011%2F04%2Fabout-dns-domain-name-server.html&ei=c-
2CVPajJsX9Uoq4gqAB&bvm=bv.80642063,d.d24&psig=AFQjCNGdnCMG0GFdu-
WJez0woceyoWL_Ig&ust=1417952354436319

14. • Imagine that you have an email you want to send
to someone in another country and it is 2 Megabytes
in size.
• When you send the file, it isn’t sent as one whole
document. Instead it is broken up into small data
packets.
• Our 2 Megabyte email would be sent in chunks of
512 bytes in size.
• Before each of these packets are sent, they are
given a header, which has the IP address it is being
sent to and the IIP address from which it was sent.
• The header also gives each packet a number, and
then records how many packets the data was split
into.

15. How do Packets get through the
Network?
• The packets, after they leave your computer, are sent
through the network knowing where they need to get
to. The packets start to head off and take the fastest
path.
• A machine called a router finds out which is the next
fastest connection and sends each packet on its way.
Throughout the journey, the packets will pass through
many different routers, possibly in many different
countries.
• This method is extremely efficient because if one of the
paths get broken or becomes too busy., they are routed
through another path instead.

16. What Happens when the Packets
Arrive?
When the packets arrive at their destination, they are put back
into order and this is made possible because of the header
number they were given before they were sent. They can now
be correctly reordered. Also, the number of packets was also
recorded, so if one packet fails to arrive, a message is sent back
to the original computer asking for a replacement package.
https://www.google.co.uk/url?sa=i&rct=j&q=&
esrc=s&source=images&cd=&cad=rja&uact=8&
ved=0CAYQjB0&url=http%3A%2F%2Fwww.ocrc
omputing.org.uk%2Ff451%2Fnetworks%2Fcircu
it_packed_switching.html&ei=uQWDVLWyBcSs
Uaqmg_AP&bvm=bv.80642063,d.d24&psig=AF
QjCNFOVx2EGMrmJpGwNlMHvzivjSf6wA&ust=
1417958447798237

18. Advantages Disadvantages
There are no tied-up lines;
therefore we could say that packet
switching makes very efficient use
of the network
The time it takes to put back all the
data packets changes every time,
which could be a down side for
time-critical information such as an
emergency signal.
It can navigate itself very easily
around broken network.
Packet-switching is not very good
for small data packages. For
example, if your data package
itself is only 600 bytes long, then
two packets of 512 bytes need to be
used, plus the address information
As the number of customers
increase, the network only has to
expand slowly, as opposed to
circuit switching when the line is
being used only two people on
either end of the line of the
telephone can use it.

20. A router is a device that transfers
data from one network to
another. It has the task of
forwarding data packets to their
destination via the most efficient
route.

21. A router has a micro-computer
inside it. This holds a
table in memory hat contains
a list of all the networks its
connected to, and with
information on how busy each
path is. This is known as the
routing table.

22. Function of the Router
When a data packet arrives, the
router does the following;
Reads the data packet's destination
address.
Looks up all the paths available to get to
that address
Checks how busy each path is at that
moment
Sends the Packet along the fastest path

23. Sources
• http://www.teach-ict.
com/gcse_computing/ocr/215_communicatio
ns_networking/IP_and_DNS/miniweb/pg8.htm#
• http://www.teach-ict.
com/technology_explained/packet_switching/
packet_switching.html
• http://www.teach-ict.
com/gcse_new/networks/hardware/miniweb/
pg4.htm
• https://www.google.com/imghp?gws_rd=ssl