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Each URL maps to the IP address of the computer that stores the Web page.
URLs are used because they are easier to remember and type than IP
addresses.
Before your browser requests a page, it asks a
server
expressed as four decimal numbers, each ranging from 0 to 255, and
separated by periods: 206.204.104.148. Every computer on the Internet
has a unique IP address.
Requesting a page
Once the browser has the IP address, it establishes a TCP
Web server and requests the page. Each page that you view requires a new
connection with the Web server. In fact, most pages require multiple
connections, since each graphic (as well as many other page elements)
requires its own connection.
Once a page is loaded, all of the connections are dropped. The process
starts over for each page on the site, though your browser does remember
the site's IP address. Some newer Web sites use HTTP 1.1 (Hypertext
Transfer Protocol version 1.1) to establish a single connection that can pass
multiple files and stay open for multiple pages.
Understanding URLs
A typical URL looks like this: http://www.symantec.com/securitycheck/
index.html. Because you might want to block some parts of a
allowing other parts of the same domain, you should understand the parts
that comprise a URL.
http://
.com
for the IP address of the Web site. IP addresses are 32-bit numbers
The program protocol used to make the connection. The
most common protocol for browsing the Web is HTTP
(Hypertext Transfer Protocol). Your browser assumes that
this is the program protocol if you don't enter one. Other
commonly used protocols include FTP (File Transfer
Protocol) and gopher.
The root or top-level domain. There are several familiar
root domains, including .com, .net, .edu, .org, .mil, and .gov.
There are also two-letter root domains for most countries,
such as .ca for Canada and .uk for the United Kingdom.
How Web information is located on the Internet
DNS (Domain Name System)
About the Internet
121
connection
to the
domain
while
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