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Uniform Resource Identifiers

For a browser to display a web page, the browser must identify the server that has the web
page, plus other information that identifies the particular web page. Most web servers have
many web pages. For example, if you use a web browser to browse www.cisco.com and you click around that web page, you’ll see another web page. Click again, and you’ll see another
web page. In each case, the clicking action identifies the server’s IP address as well as the
specific web page, with the details mostly hidden from you. (These clickable items on a web
page, which in turn bring you to another web page, are called links.)

The browser user can identify a web page when you click something on a web page or when
you enter a Uniform Resource Identifier (URI) in the browser’s address area. Both options—
clicking a link and typing a URI—refer to a URI, because when you click a link on a web
page, that link actually refers to a URI.

NOTE Most browsers support some way to view the hidden URI referenced by a link.
In several browsers, hover the mouse pointer over a link, right-click, and select Properties.
The pop-up window should display the URI to which the browser would be directed if you
clicked that link.

In common speech, many people use the terms web address or the similar related term
Universal Resource Locator (URL) instead of URI, but URI is indeed the correct formal
term. In fact, URL had been more commonly used than URI for more than a few years.
However, the IETF (the group that defines TCP/IP), along with the W3C consortium
(W3.org, a consortium that develops web standards) has made a concerted effort to
standardize the use of URI as the general term. See RFC 7595 for some commentary
to that effect.

From a practical perspective, the URIs used to connect to a web server include three key
components, as noted in Figure 5-11. The figure shows the formal names of the URI fields.
More importantly to this discussion, note that the text before the :// identifies the protocol
used to connect to the server, the text between the // and / identifies the server by name,
and the text after the / identifies the web page.
Free CISCO CCNA Routing and Switching ICND1 Study Guide
Figure 5-11 Structure of a URI Used to Retrieve a Web Page
In this case, the protocol is Hypertext Transfer Protocol (HTTP), the hostname is www.
www.certsmax.com, and the name of the web page is ccie.

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