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The Difference
between Static IPs and Shared IPs
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) 64.191.62.74. So if you type in 64.191.62.74 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 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 64.191.62.74 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 doesn’t work on a shared IP. So when
www.e3servers.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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