Internet Fundamentals
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Outline
In this lesson you will learn:
•
Evolution of Internet
•
How the internet works
•
Internet Protocol
•
Assigning IP addresses
•
Client Server Model
•
Domain Name System
•
Domain Name Extensions
•
URL
• Process of connecting to the
internet
• Internet connection from an ISP
• Modem
• Web browser
• Search engines
• Exchanging information using
internet
• Email
• Intranet/Extranet
• Proxy server
• Viruses
• firewall
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Network of Networks
Worldwide system of interconnected
Computer networks which uses
a set of protocol
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WWW
System of interconnected hypertext
document
Access via internet
(Repository of information link together
through pointers)
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Evolution of Internet…
• The Department of Defense (DOD) and Advanced
Research Projects Agency (ARPA) developed the first
network, ARPANET.
• In the late 1980s, the U.S. National Science Foundation
(NSF) started exploring ways to enable access of their
supercomputer to researchers at various colleges and
universities.
• The NSF developed a network called the National
Science Foundation Network (NSFNET).
• The NSFNET combined together with millions of other
networks to form the network of networks - the Internet.
• The Internet is a vast interconnection of computers that
connects computers across the world.
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Evolution of Internet…
• With the growing popularity of the Internet, Tim
Berners-Lee created the World Wide Web (WWW) in
1990 to introduce a user interface that would be
consistent across all platforms and could access
various document types.
• The WWW, popularly known as the Web, is a
storehouse of information. It is a collection of
several documents called Web pages, which are
interlinked with each other.
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How the Internet works
• The Internet is based on a client-server model.
• In the client-server model:
– Each computer is identified by a unique Internet Protocol
(IP) address.
– Both the client and server computers agree on a common
protocol for communication.
• The following are the components for the effective
communication over the Internet:
– Internet Protocols
– Assigning IP Addresses
– The Client-Server Model
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Internet Protocol
•
•
For effective communication, computers need to follow a set of rules
known as protocols.
Some of the Internet protocols are:
– Transmission Control Protocol (TCP) - Establishes a connection between
computers before the transmission of data. It breaks the data into small packets
and guarantees the transmission of data. TCP is a connection-oriented protocol.
– User Datagram Protocol (UDP) - Enables fast but unreliable connectionless data
transfers between the computers. UDP provides very few services for error recovery
and is used mainly for sending the messages to multiple recipients on a network.
– Internet Protocol (IP) - Routes data packets across the Internet. The process of
determining the correct path for data packets and transmitting them from one
network to another is called routing. IP can route data packets because every
network on the Internet has a unique network address. IP is a connectionless
protocol.
– Internet Control Message Protocol (ICMP) - Handles error and control messages.
– Hyper Text Transfer Protocol (HTTP) - Enables the exchange of information across
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the Internet.
Internet Protocol…
– Simple Mail Transfer Protocol (SMTP) - Enables sending email messages on the Internet.
– Wireless Application Protocol (WAP) - Provides exchange of
information over wireless devices, such as mobile phones
and Personal Digital Assistants (PDAs).
– Internet Message Access Protocol (IMAP) - Enables access
to the e-mail messages kept on a mail server.
– The Multipurpose Internet Mail Extension (MIME) protocol Allows video, audio, and binary files to be sent along with
email. It is an extension of SMTP.
– Post Office Protocol (POP3) - Enables receiving e-mail
messages on the Internet.
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Assigning IP addresses
• The Internet uses a unique number for every
computer on the network. This number is known as
the IP address.
• An IP address is a set of four numbers and is
referred to as adoted quad .
– Eg: 41.212.196.197
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Client-Server Model
• In a Client-Server Model, a client computer requests for
information from another computer known as the server.
• The server accepts requests from the client and sends
the required information back to the client.
• The client software provides an interface that allows the
user to access information from the Web server, which is
known as a Web browser.
• The two technologies commonly followed in the clientserver model are:
– Pull Technology – Based on the traditional request/reply models.
– Push Technology - Set of technologies used to send information
to a client without the client requesting it.
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Domain Name System
• A domain is a subset of the Internet, which groups
computers with similar IP addresses together.
• The domain names assigned to the computers can:
– Be up to 255 characters long.
– Have alphanumeric characters.
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Domain Name Extensions
•The domain name extensions are used to specify
the country/region or the type of organization.
•The following table lists some of the domain
name extensions that determine the type of
organization using them:
–com - Used by commercial organizations.
–edu - Used by educational institutions and educational service
organizations.
–Gov - Used by government institutions or agencies.
–Mil - Used by military organizations.
–Net - Used by organizations that support networks on the Internet,
such as ISPs.
–Org - Used by nonprofit organizations.
–Int - Used by international organizations, such as the World Health
Organization (WHO).
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The Uniform Resource Locator (URL)
• URI (Uniform Resource Identifier)
– A String of characters used to identify a name or resource.
• URL (Street Address)
– A string of characters that constitute a reference to
resource.
– Protocol://Host:Port/Path
• URN (Name of the person)
– A URI which uses theurn Scheme
– urn:issn:0167-6423
• The URN for the Science of Computer Programming (scientific
journal), identified by its serial number.
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The process of connecting to the
Internet
• The two types of components required to connect to the Internet
are:
– Hardware components
– Software components
• The hardware components required are as follows:
– A computer
– Telephone connection or cable connection or An external or internal modem
• The software components required are follows:
–
–
–
–
An Internet connection
An operating system, such as Windows
TCP/IP-protocol
Web browser
• The prerequisites to connect to the Internet are:
– Internet connection from an Internet Service Provider (ISP)
– Modem
– Web browser and URL
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Internet connection from an ISP
• An ISP is a company that provides Internet
connections.
• An ISP is connected in the following two ways:
– Dial-up connection – Using public switched telephone
network to establish a connection
– Direct connection – Connect two computers with a single
cable
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Modem
• A modem is a hardware device known as ModulatorDemodulator.
• A modem:
– Converts the digital signals from the computer to analog
signals.
– Reconverts the analog signals from the telephone cables
to digital signals and passes the signals to the computer at
the destination end.
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Web Browser
• A Web browser is a program that allows to view and
search for information on the WWW.
• The Web browser provides a GUI through which the
user interacts with the Web server.
• Types of Web Browsers are:
– Text Browsers
– Graphic browsers
• The popular Web browsers are:
– Mosaic
– Internet Explorer
– Netscape Navigator
– Mozilla
– Opera
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Exchanging Information Using Internet
• The Internet enables people around the world to
share all types of information.
• The following methods are used to exchange
information on the Internet:
– FTP
– Newsgroups
– Telnet
– E-mail
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Exchanging Information Using Internet
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FTP
– FTP is a communication protocol used to send to or receive files from a
remote computer.
– In FTP, the transfer of files takes place between two computers, an FTP
client and an FTP server.
– Using FTP, both text and binary files can be transferred on the Internet.
•
Newsgroups
– A newsgroup is a collective term for a group that is involved in
conversation on a particular subject on the Internet.
– Some of the newsgroup categories are: biz, comp, news, rec, sci, soc, talk,
humanities, Misc
•
Telnet
– Terminal Network (Telnet) is a general-purpose client-server program.
– Telnet allows the user to access any application program on the server
computer.
– Telnet allows the user log on to the server computer to gather information.
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, Return the result back to the client computer.
E-Mail
• Method of exchanging data or information from a sender
to one or more recipients.
• E-mail systems are based on store and forward model.
• E-mail was one of the first services provided by the
Internet.
• The following are the preconditions to send and receive emails:
– The e-mail address of the user
– The name of your outgoing (SMTP) mail server
– The e-mail address of the message recipient
– The incoming (POP3) mail server of the user
– The POP3 account name of the user
– The POP3 account password of the user
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Search Engines
• How web search engine works?
– Web crawling with Crawler(Spider, Ant, Automatic indexer,
bot)
• Browse the WWW in a methodical, automated manner or in a orderly
fashion
• Analyze the content of the page
• Determine how it can be indexed
– Indexing
• Data are stored in index databases
– Ranking
• Provide the pieces of content that will best answer a searcher's
query, which means that results are ordered by most relevant to
least relevant.
Additional Reading
https://moz.com/beginners-guide-to-seo/how-search-engines-operate
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Intranet
• Intranet is a private network that use TCP/IP
Protocol to share information, operating system,
all such resources within an organization.
• Benefits
–
–
–
–
–
Workforce productivity
Communication
Web publishing
Cost-Effective
Immediate updates
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Extranet
• Extranet can be concerned as an extension for
the intranet, providing control access for the
outsiders.
• Benefits
– Can exchange large volume of data
– Share details and services
– Collaborations on joint development efforts
• Drawbacks
– Expensive
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Proxy Server
• Proxy servers are software programs.
• Proxy servers act as an intermediary link between the
client, and the Web server.
• Proxy servers enable sharing of the same Internet
connection among multiple clients.
• The proxy servers mainly perform the following tasks:
– They hide the hosts on a network behind one computer.
– They have added the functions to filter URLs.
– They verify the contents of the data packets being transferred.
Additional Reading
https://www.varonis.com/blog/what-is-a-proxy-server/
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Firewall
• A firewall is a security mechanism to protect the
data in a networked computer from the other
networks with which it interacts, such as the
Internet.
• A firewall can be:
– Hardware-based
– Software-based
Additional Reading
https://www.cisco.com/c/en/us/products/security/firewalls/what-is-a-firewall.html
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Viruses
• A virus is a destructive computer program.
• A virus infects computers by replicating itself and
spreading across the network.
• Viruses can easily hide within a computer by
attaching themselves to other files or programs
because they are small.
• Viruses normally either destroy data or affect the
functions of the software applications on a
computer.
• Anti-virus programs are used to monitor computers
for viruses.
• Anti-virus programs are software that can detect
and delete viruses from computers.
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