THE INTERNET AND INTERNET TECHNOLOGY

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CHAPTER 4

• THE INTERNETAND INTERNET TECHNOLOGY

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What is the Internet?

• A collection of interconnected networks, all
  freely exchanging information
• The Largest computer network in the world (a
  network of networks)
• Exchanges information seamlessly by using the
  same open, non-proprietary standards and
  protocols, within interconnected networks
• Forms a massive electronic communications network

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The Evolution of the Internet
1969 ARPANET
1983 MILNET
Early 1980s Computer Science Network (CSNET) and BITNET
1986 NSFNET
Present Internet
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The Infrastructure of the Internet

• Commercial communications carriers provide the
  physical network backbone of the Internet
• Internet Service Providers
• Backbone providers
• Access providers
• Reciprocal agreement

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How the Internet Works

• Data are split into small portions and wrapped
  into packets
• TCP is a transport layer protocol
• IP (Internet Protocol) is a network layer
  protocol

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Addresses on the Internet

• IP address uniquely identifies each computer in
  the network
• Example 130.63.160.120
• The necessity to keep a master table with IP
  addresses on each router
• Hard to remember for people
• Uniform Resource Locator
• Domain name system (DNS) - derives the names of
  the computers

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Domain name system (DNS)

• Domain a group of networks
• Domains are organized hierarchically
• DNS is based on hierarchical database
• Variable-depth hierarchy
• Distributed database
• Exampleswww.atkinson.yorku.ca
• www.yorku.ca

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Internet Services

• Communications services
• Information retrieval services
• World Wide Web

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Communications Services Provided by the Internet

• E-mail
• Instant messaging
• Internet telephony
• Voice-over-IP
• Video conferencing

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The World Wide Web

• The Internet functions as the transport mechanism
  
• The World Wide Web - a system with universally
  accepted standards for storing, retrieving,
  formatting, and displaying information
• Web Servers support WWW application, are
  scattered all over the world
• HTTP communications standard used to transfer
  pages across the WWW

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Hypertext Transmission Protocol (HTTP)

• Web client establishes connection with server
• Web server receives a request
• Web server sends a message
• The connection is closed, if Web client does not
  use keep alive option

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Web site

• Web Site
• Home Page - first, introductory page in a web
  site
• Uniform Resource Locator
• HTML
• HTML tag
• Hyperlink
• Cascading Style Sheet (CSS)

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Web Authoring

• Standard HTML is the common denominator
• Enhancements to HTML
• Dynamic HTML (DHTML) (slide 6, Introduction to
  HTML)
• XHTML
• HTML editors, generators, publishers
• Java
• XML - extensible markup language

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Internet Applications

• Telnet a protocol which allows a user to log on
  to internet server remotely and to use own client
  computer as a terminal
• SSH ( Secure shell) secure telnet
• FTP a protocol which transfers files from and
  to Internet server computer

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Intranets

• A private network that uses Internet software and
  TCP/IP protocols
• Process business data and information
  efficiently
• Data and information search
• Urgent information delivery
• Information distribution

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Intranet operation

• Intranet documents HTML pages
• HTTP used to transmit documents
• Browsers allow to view Intranet documents
• Intranet vs. traditional networks
• HTTP and HTML platform independent
• A single input point a browser

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Extranet

• A network that links business partners to one
  another over the Internet by providing access to
  certain areas of each others corporate intranets
• Extranet infrastructure
• Virtual private network
• Firewall

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Virtual Private Network

• A secure connection between two points across the
  Internet
• Provides the means for conducting private
  communications over the public Internet.
• VPN vs. privately owned network

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Tunneling

• The process by which VPN transfers information
• Messages include data along with private protocol
  information
• Does not substitute encryption