bembry.org
Home / Technology / Inet
Directory_Logo

Internet Basics

The following set of notes corresponds to the Internet Basics module of the Internet Design course, providing students an outline of the information they are expected to understand. The corresponding reading for this module is chapter two of i-Net+ Study Guide by David Groth, et. al., pages 55-79.

History

  • Began as government project in 1973 to maintain computer communications in case portions of network were destroyed in a war. This effort produced ARPAnet (Advanced Research Projects Agency network) and the TCP/IP protocol suite.
  • In 1986 the National Science Foundation created the NSFnet, which connected ARPAnet and a number of other computer networks together.
  • In 1989, Tim Berners-Lee in Geneva, Switezerland proposes an architecture for a multimedia hypertext information system. This design comes to be known as the World Wide Web.
  • In 1993 - 1994 the first graphical web browsers are introduced, first Mosaic and the next year Netscape Navigator.
  • The World Wide Web is a portion of the much larger Internet. The Internet encompasses numerous forms of communication and data transmission, including file transfers, news groups, email, and more. The World Wide Web refers to the collection of HTML and related multimedia hyptertext documents available within the Internet.

Physical Layout

  • The Internet is comprised of LANs and individual workstations connected to Internet Service Providers (ISP), which are interconnected via a high-speed WAN.
  • An ISP is a company with a connection to the Internet backbone (or another ISP) who sells Internet connections to consumers. An ISP may also offer web site hosting, e-mail services, or other services.
  • The WANs used to connect ISPs are usually special phone lines leased from telephone companies.
  • The Internet backbone is composed of ISPs who are interconnected in a via high-speed WAN.

Domain Names and URLs

  • Domain Name Services (DNS) is a database service that links domain names with their corresponding IP addresses. This allows the computers to take a human-friendly name and translate it into a computer-friendly numeric address.
  • URLs (Uniform Resource Locators) are the addresses for information on the Internet.
  • A URL is composed of up to six different parts:
    • Protocol: describes the protocol being used. Protocols include HTTP for web page transfer, FTP for file transfers, and TELNET for a terminal emulation (command line interface).
    • Domain name: Also called the host name, this is the name registered with the Internet domain name service and generally correlates to a specific web site.
    • Port: The port number is an optional element that designates which Internet port to connect to on the host computer.
    • Path: The directory path to the file or resource being requested.
    • File: The actual name of the file or resource being accessed.
    • Query String: A query string is information added to the end of a URL to submit information to a script or program being run on the web server. These are used frequently with forms and search engines on the Internet.
    • Example: http://www.bembry.org /tech/inet/netbasics.html
  • The domain name of a URL is not case sensitive, but the path and file names are often case sensitive.
  • The Top Level Domain for a domain name is the suffix or extension at the end of a domain name (the last two to four letters after the last dot on the host name). Top level domains include the following:
    • com: Commercial organization or business.
    • edu: Educational institution.
    • org: Non-profit organization.
    • gov: Government organiztion.
    • mil: US military branch.
    • int: International organization (i.e. the United Nations)
    • net: A network organization.
    Other top level domains include country codes (DE for Denmark, JP for Japan, etc.), as well as the new domains aero, biz, coop, info, museum, name, and pro.
  • The gov, mil, edu, and int top level domains are restricted in who may own or use them, as are most of the new domains. The .com, .org, .net and .info domains are available for anyone to use. For more info on the new top level domains, see www.icann.org/tlds.
  • In order to have your own domain name, you must purchase that name from a company that is accredited by ICANN,the Internet Corporation for Assigned Names and Numbers which is responsible for ascertaining that there are no domain name conflicts. In the past there was only one company licensed to sell domains, but now the priviledge has been opened up and prices are more competitive.

Internet Communication Process

When requesting a web page while surfing the Internet, the following steps occur:

  • The browser sends the requested URL to a DNS server to be translated into an IP address.
  • Using the IP address, the request is passed to routers, who transfer the request to the intended server.
  • The server decodes the URL request and finds the resource or file requested.
  • If the requested resource requires processing, as with server-side scripting, then the server will perform the necessary processing.
  • The resulting resource is sent back to the computer that made the original request.
  • The web browser on the host computer decodes the information it receives and displays it on the screen.

Restricted access