One term you see tossed around a lot in web hosting
is IP addresses. There are basically two types of IP
addresses: static and shared. Before the difference
between the two is discussed, the definition of an IP
must be discussed.
When someone types in the address: www.yourdomain.com
that name is translated into numbers (called an IP address)
and then the computer is directed to that IP address
which is the web site. Every web site on the internet
is found not by its domain name but by its IP address.
IP addresses are in the format similar to 192.168.0.1,
four discreet blocks separated by periods. You can reach
a site by typing in the IP address alone and that will
take you directly to the site. For example www.e3servers.com
resolves (turns into) 18.104.22.168. So if you type in
22.214.171.124 directly into the address bar of your browser
you will arrive the home page of this website.
Now every single website has an IP address specifically
allocated to it. For example, every single website on
this server does not use different IP addresses. If
every site used a different IP address there could potentially
could be a problem with running out of IP addresses.
(Fortunately this is not a problem and is going to be
resolved when a new IP address standard is fully adopted).
A lot of the sites on this server, and other servers
on the internet, use one IP address for multiple sites.
So you might see joeswebsite.com and maryswebsite.com
using the same IP address. Using more than one IP address
frees up IP address which are a limited resource. Basically
what happens is that when joeswebsite.com is resolved
into the IP address, the person looking for joeswebsite.com
arrives at the server; the server then realizes that
the person is looking for joeswebsite.com and sends
that page to the person requesting it. The server basically
steps in and does a millisecond of work and saves an
IP address. Using more than one site on an IP address
is called sharing IPs or a Shared IP address. If a site
has its own IP address, and shares with no one else,
it is called a Static IP address. You can always reach
a site which has a static IP address by using its IP
address alone, but you canít reach a site using a shared
IP address by typing in the IP address alone because
when you type in a shared IP address you arrive at the
server but the server doesnít know which site you want
because you havenít told it which domain name you want.
So looking at our example above, we typed in 126.96.36.199
and arrived at www.e3servers.com we know that only www.e3servers.com
uses this address because we can get to site without
typing in a domain name and thus it must be a static
IP address. But why do you need a static IP address?
The main reason for having a static IP address is that
you can only use SSL encryption (the stuff that makes
e-commerce happen) on a static IP address. In order
for a person to transmit sensitive data over the internet
at times this data must be encrypted to prevent someone
from intercepting the information. You can only use
this encryption (called SSL) when the web site has its
own IP address (static IP). It doesnít work on a shared
IP. So when a website takes in order with a personís
credit card it needs to encrypt this data and it uses
SSL with its static IP. Another reason for having a
static IP address is that if a web site wanted to have
anonymous ftp transfers (basically where anyone can
download files off a site) the site needs to have a
static IP address to handle the anonymous ftp transfer.
Other than these two reasons there is no need for a
site to have its own IP address.