Patrick J. Kidd - Introduction to the Internet -

Introduction to the Internet

History of the Internet
Networks & the Internet
TCP/IP Protocol
Internet Addresses

Domain Name Services...

Connecting to the Internet
Internet Services (protocols)

History of the Internet
Patrick J. Kidd

History of the Internet ...

1969

ARPAnet (for military, contractors, university defense research) (DARPA = Advanced Research Projects Agency of the Department of Defense).
Designed to link computers at research sites.
The US Department of Defense needed a system that would allow all its computers to stay online even if Russia bombed (nuclear attack) some parts of the USA.

1983

MILnet (military only) +
ARPAnet (research only) until 1990

1986

NSFnet until 1995

Today

No one person or organization really controls the Internet or the networks connected to it. The Internet is a collective effort.

Networks & the Internet
Patrick J. Kidd

LAN

Local Area Network
Connects computers

WAN

Wide Area Network
Connects LANs.

Backbone

A high-speed link to connect LANs and WANs.

Routers

Special-purpose computers that provide links between networks.

The Internet

An international network of networks based on the TCP/IP protocol.
Interconnected networks.
Connects WANs and backbones.

TCP/IP Protocol
Patrick J. Kidd

Protocol

Specific set of rules

TCP = Transmission Control Protocol

Divides a message into packets (datagrams). (packet switching vs. circuit switching)
Marks each packet with a sequence number, the address of the recipient, and some error control information.
Receives packets and checks them for errors before using the sequence numbers to reconstruct the original message.

IP = Internet Protocol (Internetworking Protocol)

Each packet is routed from host to host until it reaches its ultimate destination.
Within a single data transfer, various packets might follow different routes.

Internet Addresses
Patrick J. Kidd

URL = uniform resource locator = internet address

Two types of Internet Address:

IP Address (.e.g. 198.168.49.48) is used by the Internet.
Name Address (e.g. www.dawsoncollege.qc.ca) is used by humans to access the Internet.
- http://www.dawsoncollege.qc.ca
  - http://dc1.dawsoncollege.qc.ca/~pkidd/

Two types of Local Address:

Drive letter: H:\html\index.htm
Universal Naming Convention (UNC)
A convention for naming files and other resources beginning with two backslashes (\), indicating that the resource exists on a network computer. UNC names conform to the \\%SERVERNAME%\%SHARENAME% syntax, where %SERVERNAME% is the server's name and %SHARENAME% is the name of the shared resource. The UNC name of a directory or file can also include the directory path after the share name, by using the following syntax: \\%SERVERNAME%\%SHARENAME\%DIRECTORY%\%FILENAME%.
\\ServerName\SomeFolderName\AnotherFolder\Students\A999999\home\index.htm

DNS = Domain Name System
Name Address

FQDN = Fully-qualified domain name = userid@domain

1.     Userid = username
2.     @
3.     Domain = name of the computer

Subdomain = each part of a domain is called a subdomain.

A domain must have at least two subdomains. Reading from left to right, subdomains go from specific to general. Subdomains are separated by dots (periods).

Userid@Host.Cluster.OrgName.TypeOfOrg.Country
Userid@a.b.c.d.e

a. Host = computer name most specific

b. Cluster = group name (optional) less specific

c. Organization name less specific

d. Type of organization general

e. Country code = geographic location most general
(Top level)

micco@oak.grove.iup.edu.us

A999999@dc1.dawsoncollege.qc.ca

IP Address

= Number address = Dot address = Numeric version of address

Every time you use a domain address, your system’s DNS (Domain Name Server) has to turn it into a number.

- 4 numbers between 0 and 255

- separated by dots

255.255.255.255

Connecting to the Internet
Patrick J. Kidd

Hard-Wired Connections

Terminal Connection

Your terminal (not a PC) connects to an Internet host computer.

Direct Connection

Your PC is on a LAN with an Internet connection.
Your PC is an Internet host with an IP address.

Dial-Up Connections

Terminal Emulation (VT-100, etc.)

Make your PC act like a terminal (using emulation software).

Dial-up and access the remote host (computer), which is on the Internet.

PPP or SLIP Dial-up -- Arrange for some other Internet host (computer) to act as your connection point. Your PC then uses PPP or SLIP to establish a full Internet connection over a phone line. Your PC is an actual Internet host with its own official IP address.

Other Connections

xDSL (Sympatico.ca in Montreal)
Cable (Videotron.ca in Montreal)
Cellular (?? in Montreal)
Satellite (?? in Montreal)

ISP = Internet Service Providers

Free
Hourly rate
Flat monthly rate (limited hours) + extra hours
Flat monthly rate (unlimited hours)

Login

Username
Password

Internet Services
(protocols)
Patrick J. Kidd

Usenet nntp:// news & forums

Mail (Listserv) mailto: email & mailing lists

FTP ftp:// file transfer

Telnet telnet:// remote login (libraries)

Gopher (Veronica) gopher:// URL-driven information systems

WWW http:// multimedia hyperlinked documents