Hardware Reference
In-Depth Information
InterNIC controls all address naming conventions to the right of the domain name. (In
this example, that's
biguniversity
and everything to its right). On the left side, however,
the organization that owns and hosts the domain has control. For example, Big University's
network administrators may set up the following servers, each with its own IP address:
www.biguniversity.ac.uk
for the web server
mail.biguniversity.ac.uk
for the mail server
technology.biguniversity.ac.uk
for the technology campus
Big University runs its own servers and maintains its own DNS server to provide
information about them. For example:
www.biguniversity.ac.uk
could map to
80.10.55.1
mail.biguniversity.ac.uk
could map to
80.10.55.2
technology.biguniversity.ac.uk
could map to
80.10.55.3
If you host your website on someone else's server, that hosting company maintains its
own DNS servers, and you share in their use. When you host a website somewhere, you
enter a primary and secondary DNS address and that information is populated across the
entire Internet, replicated from server to server until all the appropriate DNS servers have
been notifi ed and their databases updated to contain your information.
EXERCISE 3.11
DNS and IP Addresses
1.
Open a command-line window as you did in Exercise 3.10.
2.
Type
ping http://www.speedtest.net/
followed by the address of any website. For
example, try
ping www.speedtest.net
.
Notice that the IP address for that site appears as its status is checked.
3.
Open a web browser window, and enter the IP address you got in step 2. Does the page
load? Some servers will load the page correctly based on the IP address, and some
won't. It depends on whether a default (index) page has been set to load when no
particular page is specifi ed, and other security settings.
4.
Repeat steps 2-3 with several different websites, and compare the results. You may or
may not fi nd a site that will display using its IP address in raw form.
HTTP and HTTPS
Next let's look at Internet connectivity at a higher level. Now that you have a connection
established, what can you
do
with it? One thing you can do is request and receive web
pages. Several protocols are used to request and receive web pages on a computer. These
