Structure of the Internet
Using the Internet, people all over the world can exchange
information text, word-processor documents, pictures, video, audio,
and computer programs over computers. Although specific
organizations may develop tools or programs for the Internet, no
individual or single organization controls or governs the Internet.
However, private companies do own the Internet
backbone
(the
physical media through which the Internet traffic flows). Computers
on the Internet use a client/server architecture. This means that a
remote server provides files and services to the user's local client
computer. The speed at which the client can access the services
provided by the server depends upon the technology available. With
continuous technological advancements, the access speeds and
mechanisms are improving to allow large amounts of information to be
quickly downloaded, or retrieved, from the server.
TCP/IP
TCP/IP is the standard protocol stack used for communication over
the Internet. The TCP/IP protocol stack consists of the lower-level
protocols TCP and IP and such higher-level protocols as Hypertext
Transfer Protocol (HTTP), File Transfer Protocol (FTP), and Simple
Mail Transfer Protocol (SMTP). TCP and IP provide the low-level
functionality needed for many applications, whereas HTTP, FTP and
SMTP give you access to higher-level services, such as transferring
files between computers, sending e-mail, or identifying who is
logged on at another computer. Therefore, because of its broad range
of functions, you must install and configure TCP/IP on all computers
accessing the Internet.
Public
and Private Addresses
In
addition to understanding how TCP/IP functions, you must also know
how computers are assigned IP addresses for accessing the Internet.
The Internet Assigned Numbers Authority (IANA) allocates IP
addresses. The addresses allocated by IANA can receive traffic
from Internet locations and are known as public addresses. For a
typical small business or home office, public addresses are
allocated by an
Internet service provider (ISP),
which is a company that maintains a range of public addresses and
offers access to the Internet.
For
multiple computers in a small office or home office to communicate
on the Internet, each computer must have its own public address. The
demand for public addresses is greater than can be met by the
limited supply of available public addresses. To overcome this
shortfall in the supply of public addresses, IANA provides an
address reuse system that reserves groups of IP addresses, called
private addresses, for private networks connected to the Internet.
Private addresses cannot directly receive traffic from Internet
locations.
Internet Services
Some
of the most popular Internet services include electronic mail
(e-mail), the World Wide Web (WWW), Chat, Internet News, File
Transfer Protocol (FTP), and Telnet.
E-mail is the most popular service on the Internet. You can use it
to send messages to any user connected to the Internet.
The
World Wide Web, or the Web, is a term used to describe the
interlinked collection of hypertext documents and multimedia content
available on the Internet. Hypertext documents are files that have
been formatted for use on the Internet. You use a Web browser, such
as Microsoft Internet Explorer, to search for, locate, view, and
download information from the Internet.
Chat
programs allow you to participate in a real-time conversation with
two or more people on the Internet.
Internet News is a service that hosts electronic discussion groups
through which participants can share information and opinions. A
news client, such as Microsoft Outlook®
Express, can then be used to access these groups.
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File Transfer Protocol (FTP)
FTP
is a service that includes a server for transferring files from the
server to a client computer. Users can download files from the FTP
server by using an FTP client utility.
Telnet offers a way to remotely log on to a computer and work on
that computer. By logging on to this computer remotely, users can
access services or resources that they may not have on their own
workstation.
