how does the internet work? chapter 11. what is the internet? the internet involves millions of...
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How Does the Internet Work?
Chapter 11
What is the Internet?
The Internet involves millions of computers, connected in complex ways to a maze of local and regional networks
Origins of the Internet
1969 Department of Defense established
experimental network connecting 4 research computers
Called ARPANET 1980s National Science Foundation involved
Only scientific, research and academic institutions (no commercial traffic)
Other Developments…
1989 - E-mail connectivity thru CompuServe and MCI Mail
1991 – move towards private sector National Access Points (NAPs) Internet Service Providers (ISPs)
Communication coordinated through national and international organizations (standards)
Who Owns the Internet? No one company or country can be
considered as owner of Internet Ownership shared among various entities
Coordination: Internet Society (ISOC) Internet Engineering Task Force (IETF) Internet Architecture Board (IAB)
In the US – ICANN – Internet names and port numbers
Cost ($$$$)…
Revenue is required to offset expenses Servers, routers, communication lines, etc.
Costs must be covered by users Companies, organizations and individuals AOL – subscribers charges monthly fee
Difference Between Internet and Web?
World Wide Web is the Multimedia portion of the Internet Images, video, sound, animation, etc. Early 1990s
Technically the Web is the portion of the Internet that contains Web Servers, and Web Sites.
Internet Address
Domain Name
Logical name for computing system
www.scranton.edu
Top-Level Domain (suffix)
ICANN
IP Number
32-bit address (4 part decimal #)
ARIN / RIPE / APNIC
132.161.33.60
Internet Address…
Ethernet Address 48-bit address built into machine or Ethernet
board Refers to specific board in a local computer
Addressing
Domain Name Server (local) Network Information Server (wider area)
Maintain databases with domain names and IP numbers in binary format
Domain Name
IP Number (logical)
Ethernet Address (physical)
Laptops
Static IP address Specified manually and entered into network
tables Dynamic IP address
Dynamic Host Configuration Protocol (DHCP) Ask network for an IP address when you turn it
on (from a pool of available addresses) IP address changes each time computer is used
Web Browsers
Internet Explorer, Mozilla, Netscape Navigator, Firefox, Opera, Safari, Galeon, Konqueror
System of communicating Web documents Hypertext Transfer Protocol (HTTP)
Formatting instructions called: HTML (Hypertext Markup Language)
HTML Tags
<html> </html> Begin/End of document
<b> </b> Bold <p> </p> Paragraph <title> </title> Title – top of window <table> </table> Use in tabular form <ol> </ol> Ordered List <br> Break (new line) <img src=“mypicture.gif”> Image
JavaScript – for Interactivity
Allows for local processing (on your machine) instead of on server (server-side processing)
Browser handles some processing chores Client-Side Processing
Buttons, Check boxes, drop-down lists Advantage
Faster response to user interaction Disadvantage
Opens user to possible risks
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