Information Technology Reference
In-Depth Information
that can forward it. The message is typically sent through one or more routers (see Chapter
6) to reach its destination. It is not unusual for a message to pass through a dozen or more
routers on its way from one part of the Internet to another.
The various networks that are linked to form the Internet work much the same way—
they pass data around in chunks called
packets
, each of which carries the addresses of its sender
and its receiver along with other technical information. The set of conventions used to pass
packets from one host to another is the IP. Many other protocols are used in connection with
IP. The best known is the
Transmission Control Protocol (TCP)
. Many people use TCP/
IP as an abbreviation for the combination of TCP and IP used by most Internet applications.
After a network following these standards links to a
backbone
—one of the Internet's high-
speed, long-distance communications links—it becomes part of the worldwide Internet
community.
Each computer on the Internet has an assigned address called its
Uniform Resource
Locator (URL)
to identify it to other hosts. The URL gives those who provide information
over the Internet a standard way to designate where Internet resources such as servers and
documents are located. Consider the URL for Course Technology,
http://www.course.com
.
The “http” specifies the access method and tells your software to access a file using the
Hypertext Transport Protocol. This is the primary method for interacting with the Internet.
In many cases, you don't need to include http:// in a URL because it is the default protocol.
Thus,
http://www.course.com
can be abbreviated as
www.course.com
.
The “www” part of the address signifies that the address is associated with the World
Wide Web service, discussed later. The “course.com” part of the address is the domain name
that identifies the Internet host site. Domain names must adhere to strict rules. They always
have at least two parts, with each part separated by a dot (period). For some Internet addresses,
the far right part of the domain name is the country code (such as au for Australia, ca for
Canada, dk for Denmark, fr for France, and jp for Japan). Many Internet addresses have a
code denoting affiliation categories. (Table 7.2 contains a few popular categories.) The far
left part of the domain name identifies the host network or host provider, which might be
the name of a university or business. Other countries outside the United States use different
top-level domain affiliations than the ones described in the table.
Transmission Control Protocol
(TCP)
The widely used Transport-layer
protocol that most Internet applica-
tions use with IP.
backbone
One of the Internet's high-speed,
long-distance communications
links.
Uniform Resource Locator
(URL)
An assigned address on the Internet
for each computer.
Table 7.2
Affiliation ID
Affiliation
U.S. Top-Level Domain
Affiliations
com
Business sites
edu
Educational sites
gov
Government sites
net
Networking sites
org
Nonprofit organization sites
The Internet Corporation for Assigned Names and Numbers (ICANN) is responsible
for managing IP addresses and Internet domain names. One of its primary concerns is to
make sure that each domain name represents only one individual or entity——the one that
legally registers it. For example, if your teacher wanted to use
www.course.com
for a course
Web site, he or she would soon discover that that domain name has already been registered
by Course Technology and is not available. ICANN uses companies called
accredited domain
name registrars
to handle the business of registering domain names. For example, you can
visit
godaddy.com
, an accredited registrar, to find out if a particular name has already been
registered, and if not, register it for around $10 per year.
Millions of domain names have been registered. Some people, called
cyber-squatters
, have
registered domain names in the hope of selling the names to corporations or people. The
domain name Business.com, for example, sold for $7.5 million. In one case, a federal judge
ordered the former owner of one Web site to pay the person who originally registered the
