Datasheet
Crowder c01.tex V3 - 05/26/2008 7:16pm Page 10
Part I Laying the Foundation
user is fetching could be located directly on the domain, or within a folder within the
domain. For example, if you have a Web page called
Crowder, stored directly on the
wiley site, the format of the address would be http://wiley.com/Crowder If the
Web page, however, were stored within a folder called, say,
CWSB, the file (or Web page)
reference would be:
http://www.wiley.com/CWSB/Crowder.TheWebpageCrowder
is stored within the folder CWSB, which itself is part of the wiley.com domain.
The
www prefixing the domain name indicates that the user is referencing a networked Inter-
net server that is hosting a specially formatted document — in other words, a Web page. This
page is formatted in the markup language, HTML, a simplified subset of Standard Generalized
Markup Language (SGML). HTML is a (more or less) standardized system for manipulating, label-
ing, and ‘‘accessorizing’’ document content and structure. Chapter 4 goes into more detail about
the structure of the Web page using element tags.
IP addresses and domain names
A
ctually, the addressing scheme is a tad more complicated than the way it is represented here
because all addresses are actually numbers and not names at all. Therefore, when you type
in
yahoo.com,thisisconvertedbya
domain name server
(
DNS
) into its numeric equivalent of
209.191.93.52, which would most likely be the address of one of Yahoo’s numerous servers.
IP addresses, also known as
network addresses
, are used by the Internet to locate and retrieve
data from specific hosts within a specified network. Most Internet users access the Internet through
an Internet service provider (ISP) that has a range of IP address available. These are assigned by
the nonprofit corporation
Internet Corporation for Assigned Names and Numbers
(
ICANN
). These
addresses are portals or doorways to the Internet, and are used by multiple users for varying lengths
of time. If they checked their IP addresses, users might note that addresses dynamically change each
time they log off and log on to the Internet. If their IP number is, for example, a 172.16.x.x network
number, that address is internal to the ISP and not a routable Internet address — even though,
through it, users have access to the Internet features to which they have subscribed.
run ipconfig
is one of several ways to check the user IP address and default gateway. The
subnet mask
,which
also appears in the data about IP addresses, is for another book.
Another great way to learn your IP address on the Internet, rather than your poten-
tially internal address, is
www.whatismyip.com.
Use of HTTP and FTP
T
here may be some confusion regarding the use of HTTP and File Transfer Protocol (FTP) as Web
transport protocols
because both transfer files. The distinction would be that HTTP is used to
transfer Web page content to a browser from a Web server and the service is one way: from server
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