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| 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. |
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| 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.navicosoft.com
resolves (turns into)
67.19.28.98. So if
you type in 70.84.113.242/~asif
directly into the
address bar of your
browser you will arrive
the home page of this
website. |
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| 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 marywebsite.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 joewebsite.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 can't
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
doesn't know which
site you want because
you haven't told it
which domain name
you want. So looking
at our example above,
we typed in 70.84.113.242/~asif
and arrived at www.navicosoft.com
we know that only
www.navicosoft.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? |
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| 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 doesn't work on
a shared IP. So when
www.navicosoft.com
takes in order with
a person's 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. |
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