2. Internet
• Interconnection of networks worldwide
• Allows communication and sharing of
information between connected systems
• Uses Internet Protocol
• Popular applications
– World Wide Web
– E-mail
– File transfer & sharing
– Voice and video streaming
3. Any difference between
‘Internet’ and ‘internet’?
• YES!
• internet is interconnection of networks
• Internet with capital 'I' refers to the internet as in
the world wide web
• Confused? Read again!
4. What is needed to visit a
website in the Internet?
• A machine installed with TCP/IP protocol
• Gateway / Router / Proxy server
• DNS server
• A browser program
• The URL / IP address of the website
5. TCP/IP
• TCP and IP are communication protocols for the
Internet
• Try this
– Check the network properties of your machine to find
out whether your machine has TCP/IP installed. Write
the IP address of your machine. You can use ‘ipconfig’
command to find your machine’s IP address.
– Use the ‘ping’ command to check whether you have
connectivity with your friends’ machines.
– Type ‘ping/?’ in the command prompt to view the
options of this command. If you want to continuously
ping, what option will you use?
6. Internet Protocol
• Every computer that communicates on a network
needs its own IP address
• Static and Dynamic
– Static addresses are permanently configured for a
machine
– Dynamic addresses are given by DHCP servers
– Question: When you are connected to Internet
through your home Streamyx, what type of IP are
you getting: static or dynamic? Why?
• Public and private
– Public IPs can be seen on the Internet
– Private IPs can only be used within a broadcast
domain
• ranges associated with addresses 10.0.0.0,
172.168.0.0, and 192.168.0.0 through 192.168.255.0.
• Question: what type of IP is your machine’s? Private or
public? Is it static or dynamic?
7. IPv4 and IPv6
• Two standards of IP addresses being used today
• IPv4
– has 4 billion addresses but they are not enough for
the growing number of machines connected to the
Internet
• IPv6
– has 2128 addresses=3.4x1038 addresses
– ISPs are moving into implementing IPv6 addresses
because of its many advantageous features
• Fact finding: Find the role of National Advanced
IPv6 Center in the implementation of IPv6
technology in Malaysia. Why need a National
organisation to implement IPv6 addresses? Visit
http://www.nav6.org to find your answers. (15
minutes)
8. Domain name
• The name of a computer on the Internet
• The domain name service (DNS) converts domain
names to IP addresses
• Who runs the DNS?
– Millions and millions of servers
– DNS database is the biggest database in the world
• Some Top Level Domains - .com, .org, .net
• nslookup is a command that you can use to check
whether a domain name and its IP are available in
a DNS server
9. • Try this
– Find whether the domain name nav6.org is
available in OpenDNS and 202.188.0.133
servers
– How to do this?
• Search the OpenDNS IP from the Internet and
use command nslookup – OpenDNS-IP nav6.org
• Now try the same command again with DNS IP
202.188.0.133
• See the results. Is the name found in the DNS
servers?
10. URL
• Uniform Resource Locator
– the global address of documents and other resources on the World
Wide Web
– The first part of the address is called a protocol identifier and it
indicates what protocol to use
– The second part is called a resource name and it specifies the IP
address or the domain name where the resource is located
– For example, the two URLs below point to two different files at the
domain nav6.org. The first specifies an executable file that should
be fetched using the FTP protocol; the second specifies a Web
page that should be fetched using the HTTP protocol:
» ftp://www.nav6.org/sample.exe
» http://www.nav6.org/v3/index.html
11. Internet Browser
• A program used to view web pages
• Question: Can you name some popular
internet browsers?
12. A web page
•Is created using HTML tags.
Try this: Open Notepad and type the tags and statements
below.
Save it with extension .htm or .html. Then open it with an
Internet browser.
<html>
<head></head>
<title>This is my title</title>
<body>
<H1>Hello world</H1>
<H2>Hello world</H2>
<H3>Hello world</H3>
</body>
</html>
13. Creating a web page using Microsoft Word
• You can create a web page easily using
Microsoft Word.
• You can create a page by just creating a
document and saving it as a web page.
• If you have never tried it, try it!
14. Protecting your PC
• What should you do?
– Install antivirus – Try this by downloading a free
antivirus like AVG or Avira antivirus and installing
them in your PC
– Enable your PC firewall – Try this
– Update your operating system regularly – Try this by
using Windows Update
– Install a reliable anti-spyware – Try this by installing
Windows Defender. You can also download and
install Search & Destroy Spybot
• What else should you do?
– Don’t accept applications from the websites if you not
sure of their contents
– Don’t open attachments from your emails if they look
suspicious
