Internet Fundamentals
The Internet’s History
• 1969 – ARPANET (Advanced Research
Project Agency NETwork)
• Developed by the Department of Defense
• Connected universities and defense bases
• 1973 – ARPANET connects to Europe
2A-2
ARPANET 1973
2A-3
The Internet’s History
• Mid-1980s – NSFNet
• Network between supercomputers
• Internet was the link to ARPANET
• No commercial traffic allowed
• 1990s
• ARPANET shut down
• NSFNet abandoned
• Commercial networks take over
2A-4
Today and the Future
• Thousands of networks
• Hundreds of millions of users
• Huge co-operative community with no
central ownership
• Anybody can access it
2A-5
THE INTERNET’S MAJOR
SERVICES
2A-6
1. E-mail
• Stands for electronic mail
• One of the “killer application” for the
internet
• Use E-mail client
• E.g. outlook express
• Web based email service
2A-7
E-mail (contd)
• E-mail addresses
• saleem@gmail.com
• Unique id
• Email server
• Or email service provide e.g hotmail.com
2A-8
• COM – COMMERCIAL
• .EDU- EDUCATIONAL
• .ORG – NON PROFITABLE ORGANISATIONS
• .NET – NETWORKS
• WWW.IBRAHIM.CO.SA
• WWW.IBRAHIM.CO.US
• .OM, .JP, .UK, .AE, .MY, .SG
2A-9
E-mail (contd)
• Mail Server
• When you send an email, message is stored on
email server, until the recipient can retrieve it
• Many mail server use Post Office Protocol (POP)
• Also called POP servers
• Internet Message Access Protocol (IMAP)
• Used by local clients to retrieve email from
email servers
2A-10
E-mail (contd)
• Mail Server
• Simple Mail Transfer Protocol (SMTP)
• Used by mail servers to send/receive messages
2A-11
E-mail (contd)
• E-mail features
• Audio, Video, Images can be sent as
attachment
• Reply, Reply All, Forward, Delete, CC, BCC
• Listserv
• Lists of e-mail addresses
• Each address gets the e-mail
2A-12
Spam: Unwanted Junk E-Mail
•Delete without opening the message
•Never reply to a spam message!
2. Information Browsing
• “To retrieve and display specified
information stored in one or more
computers connected to a computer
network”
• Implies interactivity
2A-14
Menu Based Browsing
• Earliest browsers were menu based
• Gopher
• Menu is presented
• User selects a menu item
• Gopher software will search table to find out where the
required information is stored
• May be on another computer
• Retrieve information and display
• Look up process hidden from user
2A-15
Hypertext Based Browsing
• A system in which documents scattered across
many Internet sites are directly linked, so that a
word, phrase or an image in one document
becomes a connection to a document in a
different place
• User clicks a word/image
• Document is retrieved
2A-16
Hypertext Based Browsing (contd)
• Hypertext systems provide an easy way to
manage large collections of data scattered
world wide
• Documents can be interconnected
• Facilitates non-linear reading
2A-17
World Wide Web
• Billions of documents, stored in different places,
linked together in some manner
• “Web” of interconnected information
• Collection of documents and links spread all over
globe
• “World wide web”
• Developed in 1993 by Tim-Berners Lee
2A-18
How the web works?
• HyperText Transfer Protocol (HTTP)
• Special protocol used by web to supports hypertext
documents
• HyperText Markup Language (HTML)
• Hypertext documents are encoded in HTML
• A notation to mark keywords in documents
• Allows author to embed hypertext links
2A-19
How the web works? (contd)
• Uniform Resource Locator (URL)
• Method of naming documents or places on
the Websites
• String of characters that identifies
• the type of document,
• the computer the document is on,
• the directories and subdirectories the document is
in, and
• the name of the document.
2A-20
How the web works? (contd)
• Uniform Resource Locator (URL) (contd)
http://www.mu.edu.sa/ccis/index.htm
• Protocol : http
• Domain name: www.mu.edu.sa
• Directory name: ccis
• File name: index.htm
2A-21
How the web works? (contd)
• Hypertext Browser
• Marc Anderson developed Mosaic web browser
• Some popular browsers today are
• Internet Explorer
• Firefox
• Chrome
• Netscape communicator (successor to Mosaic)
• URLs can be typed in a browser
2A-22
How the web works? (contd)
• Web pages and Websites
• A hypertext document is called a web page
• Collection of related web pages is a website
• A Web page is a document on the World Wide Web
on a Website that can include text, pictures, sound,
and video
2A-23
How the web works? (contd)
• Helper Applications
• Many websites feature multimedia content
• Browsers alone cannot display every type of
content
• Multimedia files requires special applications
in order to be played in real time
• Also called plug-in applications
2A-24
How the web works? (contd)
• Helper Applications (contd)
• Plug-ins support several types of content
including audio and video streaming
• Content is sent in a continuous stream (still in
packets) from web server to browser
• Plug-in receives first portion and buffers it
• First portion is played while next portion is
buffered
2A-25
Streaming Audio
2A-26
Some Common Plug-ins
Searching the World Wide Web
• The Web is unorganized
• Directories
• Categorize the Internet
• Search engines
• Find sites by keyword
2A-28
Searching the World Wide Web
• Resource Directories
• Directory separates subjects in categories
• Typically employ human experts
2A-29
Resource Directory
2A-30
Searching the World Wide Web
• Search Engine
• Search using keywords
• E.g. Google.com
• Offer advanced options as well
• Do not use humans to index documents
• Automated programs called “web crawlers”
• browse world wide web in a systematic manner
• Pick keywords
• Create index
2A-31
Other Internet Features
• File Transfer Protocol (FTP)
• Allows you to access any computer connected to the
internet and download files
• FTP Site is a collection of files housed on an FTP Server
ftp://ftp.xcollege/admission-rules
• Remote server, ftp.xcollege, will prompt for a login id
and password
• Public FTP archives accept “anonymous” as user id
2A-32
Other Internet Features
• Telnet
• Logging on to a remote computer and using its
facilities
• telnet: <domain name of computer> or IP
address
• Login ID and Password
2A-33
Other Internet Features
• Internet Relay Chat (IRC)
• Real time communication system
• Multi-users with many channels (rooms)
(Whatsapp Groups)
• Channels are dedicated to a topic
• All users can read the comments
2B-34
Other Internet Features
• Instant messaging (IM)
• Private, real-time communication
• Message sent only to listed users
• Buddy lists contain IM names
2B-35
Other Internet Services
• Peer-to-peer (P2P) services
• User computers are connected together
• No centralized organization
• Users can communicate directly
• Users can share files
2B-36
Other Internet Services
• Internet Radio
• Audio from radio station is stored in high speed
disk memory of server
• Person wishing to listen to broadcast logs on to
the server and listens to it by downloading it
using internet
• Intermittent reception due to packet switching
• Start with delay
2B-37
Other Internet Services
• Internet Telephony
• Normal telephony is circuit switched
• Expensive
• Talk over packets
• Low cost
• Quality may not be the best
• Voice over IP (VoIP)
2B-38
Other Internet Services
• Video Conferencing
• Voice + Video over Internet
• Different standards exist
2B-39