Information Technology Reference
In-Depth Information
the traffic on a particular day is heavy or light. Expenses largely
have to do with setting up and maintaining the network rather than
communicating individual messages.
For this reason, what you're charged for Internet usage typically
depends on the materials you need to buy to establish connections
(cables, computers, junction boxes, and so on) and the general level
of capacity you anticipate. Fast lines may be more expensive to in
stall and maintain than slow lines, for example, but your needs may
make them more useful to you than the other. Once equipment is in
place, you can send many messages or just a few with virtually no
change in cost. For this reason, charges for the Internet to you, your
school, or your company usually are not associated with individual
messages. You pay a flat fee (perhaps monthly) for a level of service
to support the infrastructure, but you do not pay per message. Part
of your payment to an ISP then goes toward the NAP for the na
tional infrastructure.
Once you have connectivity to the Internet, you have access to an
incredible wealth of information and the ability to communicate
with people around the world. For many people, these advantages
make up for the expense of a monthly subscription to an ISP. In ad
dition to email, the Internet allows you to navigate, or surf, through
Web sites that cover virtually any topic. You probably have some fa
vorite Web sites, and their names all conform to a standard format.
Let's turn now and take a look at what's behind an Internet address.
When you type in a Web address, you provide the computer
with the information it needs to find the location you are trying to
access. All locations on the Internet may be described at three lev
els: the
domain name
, the
Internet Protocol number (IP number)
,
and the
Ethernet address
. Let's now examine each level.
Domain Name: The domain name is the logical name for a com
puting system attached to the Internet. If your school hosts a Web
site, then its domain name is likely included in the Internet addresses
for its Web pages. For example, cs.utexas.edu is the logical name as
*(From Dale and Walker,
Abstract Data Types
, pp. 144-146.)
