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Basic Internet Concepts

What is the Internet?

A network of networks that connects computers all over the world.

The name for a vast, world wide System consisting of people, information, and computers.

Practical or commercial point of view: a vast collection of information that can be search and retrieved electronically.

Technical point of view A network of tens of thousands of computer networks.
Technically, what distinguishes the Internet is its use of a set of protocols called TCP/IP (Transmission Control Protocol/Internet Protocol).

Social point of view a network that allows millions of people throughout out the world to communicate with each other, sending and receiveing messages.

A collection of networks throughout the world that agree to communicate using specific telecommunications protocols, the most basic being the Internet protocol (IP) and transmission control protocol (TCP), and services supplied by those networks.

The Roots of the Internet lie in the project called the ARPANET which was sponsored by the U.S. States Department of Defense Advanced Research Projects. (ARPA)

History of the Internet

Hobbes' Internet Timeline Copyright (c)1993-9 by Robert H Zakon.

Hobbes' Internet Time Line

The History of the Internet

A Brief History of the Internet

Networks on the Internet

The Internet is a large ``network of networks.'' There is no one network known as The Internet; rather, regional nets like

etc. are all inter-connected together into one great living thing, communicating at amazing speeds with the TCP/IP protocol. All activity takes place in ``real-time.'


The UUCP network is a loose association of systems all communicating with the UUCP protocol. (UUCP stands for `Unix-to-Unix Copy Program'.)

It's based on two systems connecting to each other at specified intervals, called polling, and executing any work scheduled for either of them.

Most UUCP was done with Unix equipment, although the software has since been implemented on other platforms (e.g. VMS).

BITNET BITNET (the ``Because It's Time Network'') is comprised of systems connected by point-to-point links, all running the NJE protocol.

It's continued to grow, but has found itself suffering at the hands of the falling costs of Internet connections. A number of mail gateways are in place to reach users on other networks.

Network Connections on the Internet

These links are paid for by each institution to a local carrier (for example, Bell Atlantic owns PrepNet, the main provider in Pennsylvania). Also available are SLIP connections, which carry Internet traffic (packets) over high-speed modems.

UUCP links are made with modems (for the most part), that run from 1200 baud all the way up to as high as 38.4Kbps.

The Networks, the connections are of the store-and-forward variety.

The systems do their UUCP traffic over TCP/IP connections, which give the UUCP-based network some blindingly fast ``hops,'' resulting in better connectivity for the network as a whole.

UUCP connections first became popular in the 1970's, and have remained in wide-spread use ever since.

BITNET links mostly take the form of 9600bps modems connected from site to site.

Computers on the Internet

Each computer on the Internet is called a host computer

On the Internet, the term "host" means any computer that has full two-way access to other computers on the Internet.

Numeric Computer (IP) Addresses

Each host computer on the Internet has a unique number, called its IP address

IP address an Internet address in numeric form
Static IP Address-permanent IP address which you use each time you log in
Dynamic IP Address-non-permanent IP address, assigned each time you log in

The current version of IP, IP version 4 (IPv4), defines a 32-bit address

Domain NameIP Address
www. eas.asu.edu129.219.30.21

IP addresses and domain names aren't assigned arbitrarily. An application must be filed with the Network Information Center (NIC), either electronically (to or via regular mail.

Finding IP Addresses

Domain and Host Names

Host name(domain name) Internet name for a network or computer system. The name consists of a sequence of characters separated by periods.

Domain --the last to parts of the host computers name.
Top-level domain -- the last part of the domain name.
Second-level domain-second-to-last part of the domain


Top-level domaingov
Second-level domainloc

www identifies this computer as the Library of Congress's Web server
loc tells you that the server is on the Library of Congress's network
gov the top level domain tells you that the server is part of a government system
Two types of top-level domains

  1. Organization domains three letter top-level domain based on type of organization
    com commercial
    edueducational institution www.
    intinternational organization
    netnetworking organization
    orgnon-profit organization

    The top-level domain names are administered by IANA and its delegate agencies.
    Domain names are assigned by Network Solutions'InterNIC registration services at

  2. Geographical Domains two-letter top-level domain based on an abbreviation for a particular country
at      Austria         au      Australia               ca      Canada

fr France us United States jp Japan

Geographical domains are assigned by the country where the organization that owns the host computer is located.

Servers, Clients, and Ports

Server-a computer system or program which provides information to other programs called clients

Clients -a program that you use to access a resource provided by a server. 1993 Marc Andreesen (student a University of Illinois) released a new program called Mosaic Port: A logical connection to a remote computer in order to provide a particular service identified by a port number
Port number, when connecting to a remote Internet host, the number that describes the type of service requested.

Port Number                          Internet Service

21 FTP (file transfer)
23 Telnet (remote login)
25 SMTP (mail relaying)
80 World Wide Web
110 POP3(storage of incoming mail)
194 IRC 9online chat)
532 Usenet newsgroups(discussion groups)

Domain Name System (DNS) TCP/IP service translates an address from a domain name to an IP address and vice versa

The domain name system (DNS) is the way that Internet domain names are located and translated into IP (Internet Protocol) addresses.
A domain name is a meaningful and easy-to-remember "handle" for an Internet address.
Developed in 1984

Internet Services

Types of Internet Accounts


Point-to-Point Protocol (PPP) allows a computer with a modem to make a TCP/IP connection over a phone line

Serial Line IP (SLIP) (obsolete protocol), used to support a TCP/IP
connection over a phone line or over a serial connection

Internet service providers (ISP) an organization or business offering public access to the Internet, usually using a telephone dial-up connection
Provides unlimited access to the Internet and the World wide Web for a flat monthly fee

UNIX Shell Accounts

Shell Account

Advantages of a shell account Online Information Services-a commercial service that enables you to connect to and access its proprietary information system

Provide access to databases. electronic meeting places, and the Internet to subscribers equipped with telephone-linked microcomputers
America Online(AOL)-the worlds most popular
CompuServe(CIS)-one of the oldest
Microsoft Network(MSN)
Prodigy-not as popular as the three above

Telephone, Cable, and Satellite Connections

Accessing the Internet via the Telephone System ( Items Needed)

Moving Data Across The Phone Line

Modem is a device that allows two computers to communicate over a standard phone line.

Modems take a digital signal, from the computer's serial port, and modulate it into an analog form, so you can send it over the phone line.

This is accomplished by changing the digital information of a computer (which is stored as a series of 0's and 1's known as the binary code) into a tone, or frequency, that can be sent over the phone to another modem.

The hiss you hear when you pick up a phone during a modem connection is this analog form.

The receiving modem will then change the sent tones back to digital information, which can be understood by the receiving computer.

This process gives the modem its name, derived from the two words modulate and demodulate, which describe the two primary functions of a modem.

When you read off a piece of paper to someone over the phone, you're being a modem - converting digital information to an analog form (your voice).

The speed of the modem, is calculated in bits per second, where roughly eight bits equals a character of information. Think of this as a page per second.

There are two types of modems -- internal and external.

  1. An internal modem is placed directly into a computer's communications (COM) port, which is located inside the computer.
  2. An external modem, is kept outside the computer.
ISDN telephone service Asymmetric digital subscriber line (ADLS) "Cable Modem" refers to a modem that operates over the ordinary cable TV network cables.

Cable Modems carry digital data more than 1000 times faster than plain old telephone system (POTS)

You connect the Cable Modem to the TV outlet for your cable TV, and the cable TV operator connects a Cable Modem Termination System (CMTS) in his end (the Head-End).

Satellite Dishes

Tips for choosing an ISP