1. How Does the Internet Work? Chapter 11

2. What is the Internet? The Internet involves millions of computers, connected in complex ways to a maze of local and regional networks

3. Origins of the Internet 1969 Department of Defense established experimental network connecting 4 research computers (UC@Los Angeles, UC@Santa Barbara, SRI International, U. of Utah) Called ARPAnet 1980s National Science Foundation involved Only scientific, research and academic institutions (no commercial traffic)

4. 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)

5. 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

6. 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

7. Difference Between Internet and Web? World Wide Web is the Multimedia portion of the Internet Images, video, sound, animation, etc. Early 1990s

8. Internet Address  Domain Name  Logical name for computing system www.scranton.eduwww.scranton.edu  Top-Level Domain (suffix)  ICANN  IP Number  32-bit address (4 part decimal #)  ARIN / RIPE / APNIC  132.161.33.60

9. Internet Address… Ethernet Address 48-bit address built into machine or Ethernet board Refers to specific board in a local computer

10. 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)

11. 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

12. Web Browsers Internet Explorer, Mozilla, Netscape Navigator, Firefox System of communicating Web documents Hypertext Transfer Protocol (HTTP) Formatting instructions called: HTML (Hypertext Markup Language)

13. HTML Tags Begin/End of document Bold Paragraph Title – top of window Use in tabular form Ordered List Break (new line) Image

14. 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