1. Fundamentals of
Internet and World Wide Web
Lecture 02
By:
Khalid Khan
Department of Computer Science
University of Peshawar
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2.  A Brief Introduction to  Web Servers
◦ Web Server Operation
Internet ◦ General Server Characteristics
◦ Origins ◦ Apache, IIS etc.
◦ What Internet is?  Uniform Resource
◦ IP Addresses Locators
◦ Domain Names ◦ URL Formats
◦ URL paths)
 The World Wide Web  HTTP
◦ Origins ◦ Request Phase
◦ Web or Internet? ◦ Response Phase
 Web Browsers  FTP
 Searching on the
Internet
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3.  1958 – USSR launches Sputnik, first artificial earth satellite.
 1960s – the US Department of Defence (DoD) gave the
concept of a large scale computer network.
 1969-Software called Network Control Protocol (NCP)
provided communication between the hosts.
 The US DoD’s Advanced Research Project Agency (ARPA)
funded the construction of such network – called ARPAnet.
◦ ARPA Net was text based.
◦ Communicate through email.
◦ Technique (packet switching)
◦ Protocol (TCP)
◦ ARPA reach to the development of IP (Internetworking protocol)
creating a network of networks.
◦ Combined set is called TCP/IP
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4.  1970s and early 1980s – other networks such as BITNET and
CSNET were also created but never became dominant
networks.
 1986 – NSFnet, sponsored by National Science
Foundation(NSF) – initially connected five universities, but
after establishment it became available to other institutions
and laboratories too.
 1990 – NSFnet replaced ARPAnet
 1992– NSFnet connected more than 1 million computers
around the world.
 1995 – a small part of NSFnet returned to being a research
network, and the rest became known as INTERNET
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5. A Brief Introduction to Internet
1985 1993
NSFNET founded Web Browser
1969 1983
by The National “Mosaic” invented
ARPANET DOD Mandated
Science by Mark Andreesen
R&D Project Adoption of TCP/IP
Foundation
ARPANET INTERNET
1974 1983
Vinton Cerf ARPANET Split 1991
and Robert Kahn into ARPANET and World Wide Web
Initiated TCP/IP MILNET Released by
Tim-Berners Lee

6.  The Internet is a huge collection of computers
connected in a communications network.
◦ The computers are of every manageable
size, configuration, and manufacturer.
◦ Some of the devices connected are not computers at all
e.g. plotter and printers etc.
 All of these diverse devices to communicate with
each other using a protocol, TCP/IP.
 Each computer on a network is assign a unique ID
called IP address, just like people home or street
address.
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7.  For people, Internet nodes are identified by names, for
computers, they are identified by numeric addresses.
◦ If one wants to send data to the computer on same
network, he needs the physical address of the computer to
which data is intended to be sent.
◦ But if the receiving computer lies on another network, or
Internet for example, then IP address of the recipient is
required to address it.
 The Internet Protocol(IP) address of a machine is a
unique 32-bit number (IPv4), written in the form of
numbers separated by dots(.).e.g. 191.57.126.0.
 New IP standard, approved in 1998, is IPv6 in which the
address space was expanded to 128bits.
◦ This change is essential to face the rapid growth of
computers.
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8.  A domain name represents a group of hosts on the
Internet.
 A full domain name is a sequence of labels separated by
dots
 It combines a host name and a TLD to form a fully
qualified host name which provides a user friendly way to
uniquely identify a site on the Internet.
 The DNS translates fully –qualified names into IP
addresses.
 For example a yahoo website can be reached by typing
http://www.yahoo.com or alternatively you can type the
IP address of the yahoo server (e.g. like 207.168.92.4) in
to browser.
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9.  We would go crazy if we would have to remember the
IP addresses of all the web sites that we wanted to visit
 The Domain Name System translates between domain
names and IP addresses of devices connected to the
Internet
◦ A domain name (a part of the URL) is a unique
alphanumeric name such as upesh.edu
◦ The top level domain name is edu and the
secondary level domain name is upesh in the above
example (there could be up to 127 levels, but more
than 4 is rare)

10.  The fully qualified host name of a computer on
Internet has three major parts:
 The host name: The hostname is the name of the
particular host on the internet.
 The domain name: A domain name is usually the
name of the company that owns the site or a word
or phrase that otherwise describes the site.
 Domain encapsulate host names
 The TLD: It usually refers to the type of
organization that owns the domain name e.g.
com, org, edu, gov, pk etc
. www.university.peshawar.net 10

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12. Domain Name and Host
IP ADDRESSES DOMAIN NAMES
Every device connected
has a unique 32-bit Human
DNS Readable
address
cnn.com
Every device
Translation connected has an
Machine Readable alphanumeric
Between
e.g. 151.196.19.22 address
domain Names
and IP Addresses

13.  Domain Names.
 Generic top level domains
 .com
 .biz
 .info
 .edu
 .mil
 .net, etc.
 Country codes or Country Domain
 .pk, .jp, .cn, .us, etc.

14. 1945 – Vannevar Bush
1945 – Invent Memex
?
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15.  1965 – Ted Nelson
◦ Coined the term “hypertext”
◦ Project: “Xanadu”:
◦ “A File Structure for the Complex, the Changing, and the
Indeterminate.” 20th National Conference, New
York, Association for Computing Machinery, 1965.
 In 1989, Tim Berners-Lee at CETN (European
Laboratory for Particle Physics) proposed a new
protocol for the internet as well as a system of
document access to use it.
 This new system was called World Wide Web
(WWW) which allow scientists around the world
to use the Internet to exchange document to
describe their work.
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16.  The release of the first graphical interface, Mosaic, in
February 1993.
 1995 – 2001
◦ “Dot coms” like AOL, Yahoo, Netscape,
◦ Google
◦ Internet Explorer”
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17.  The Internet and the Web are not the same thing.
 Internet is a collection of computers and other devices
connected by equipment that allows them to communicate
with each other.
 The web is a collection of distributed documents referred to
as “pages” located on computers (servers) all over the world.
 Servers store hypertext markup language(HTML) files and
respond to requests.
 The Internet was quite useful before the Web was developed,
and is still useful without it.
 However, most users use Internet through the use of Web.
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18. The web is based on a three-part architecture.
HTML
HTTP
GUI
Databases
TCP/IP-based network GUI Content
Web clients Web Servers Software
applications

19. The Web operates in a client/server configuration:
 Client: A client computer is one which requests for services to a
server.
 Client uses a software called Web Browser for this purpose.
 Server: A computer that send responds to a client request, using
a software called Web Server.
 HTTP is the most common protocol used for the communication
between browsers and servers.
Examples of browsers are Microsoft Internet Explorer, Netscape
Navigator, Opera, Chrome, Mozilla Firefox etc.
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20.  Web servers are programs that provide documents to the
requesting browsers.
 Servers are slave programs:
◦ A web server stores web pages and delivers those pages upon
client request. A web server software is installed on the web
server.
◦ They act only when requests are made to them by browsers
running on other computers on the Internet.
 Examples of Web Servers are:
 Microsoft Internet Information Server(IIS)
 Apache
 SunONE etc.
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21.  URLs are used to identify documents (resources) on the
Internet.
 Different types of resources identified by different forms of
URLs, but with same general format:
 Scheme: object-address
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22.  Each page of information on the web has a unique address
called the URL at which it can be found.
http://faculty.uscupstate.edu/atzacheva/lecture1.html
The document
can be obtained Host Name - Path to the Web File Name Denotes that the File
using the The Name of Page is Written in HTML
Hypertext Web Server HyperText Markup
Transfer Protocol Language
(HTTP)
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1 3
Host Name
Protocol File Name

23.  Scheme: object-address
 Scheme: a communications protocol
 Common schemes include
http, ftp, gopher, telnet, file, mailto, and news.
 Most important is HTTP, which supports the Web, and used to
request and send eXtensible Hypertext Markup Language
(XHTML) documents.
 In case of using HTTP, the form of the object address of a
URL is:
 http://fully-qualified-domain-name/path-to-document.html
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24.  All Web communications transactions use the same
protocol, the HTTP.
 The current version of HTTP is 1.1, defined by World Wide
Web Consortium (W3C) in June 2011, as
 HTTP consists of two phases:
 Request phase
 Response phase
 Each HTTP communication (request or response) between a
browser and a Web server consists of two parts:
 Header – contains information about communication
 Body – contains the data of the communication, if there is
any.
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25. i. The Request Phase ii. The Response Phase
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26.  FTP works on the client/server principle.
 A client program enables the user to interact with a server in
order to access information and services on the server
computer.
 Files that can be transferred are stored on computers called
FTP servers.
 To access these files, an FTP client program is used.
 This is an interface that allows the user to locate the file(s) to
be transferred and initiate the transfer process
 There are two modes of transfer in FTP:
 ASCII is used only for files saved in ASCII format (this includes
Postscript files)
 Binary is used for files that are formatted and saved using a
word processing software like WordPerfect
(.txt), spreadsheets (.xls), images (.jpg, .gif), and many
executable programs (.exe) and videos (.avi).
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27.  Searching the Web
 The two most basic and commonly used Web-based search
tools are:
 Directories
 A directory enables you to search for information by selecting
categories of subject matter.
 The directory separates subjects into general
categories, which are broken into increasingly specific
designers.
 http://www.lookmart.com
 Search Engines
 A search engine lets you search for information by typing one
or more words.
 The engine then displays a list of Web pages that contain
information related to your words.
 http://www.google.com.pk/ 27

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