Shared and Dedicated IP Address
What is IP address?
An Internet Protocol address (IP address) is a unique identifier assigned to each device connected to a computer network that uses the Internet Protocol for communication.
Every computer (and server) on the Internet has an IP address. When you buy a hosting plan it is hosted on a server. When you add a domain name to your hosting the DNS system using variety of nameservers assigns an IP address to your domain name.
A typical DNS A record looks like this:
somedomain.com. IN A 220.127.116.11
And if anyone enters your domain name in a web browser they will see your website on their screens.
When most hosting users (having their plans on the same hosting server, of course) have the same IP address assigned to their domain names they are sharing this IP address.
So a definition of a shared IP address sounds like this: shared IP address is a single IP address assigned to multiple domain names at the same time.
When one IP address is assigned to only one hosting account this IP address is dedicated.
Shared IP address
The usage of shared IP address brings some disadvantages and we'll briefly mention the most important of them.
SSl Certificate sighned by Certification Authority (CA)
If you want to install SSL certificate signed by a CA you need a dedicated IP address.
Email Sending Problems
If the shared IP is blacklisted because of sending spam for whatever reason (intentionally, website or mail account been hacked, etc.) - you'll be unable to send an email from your all domains in your account until the hosting administrator completes the procedures of the anti-spam or reputation services which sometimes may take more than 24 hours to recover.
Dedicated IP address
A dedicated IP (Internet Protocol) is a unique Internet address dedicated exclusively to a single hosting account and this fact leads some important advantages.
You can install any Certification Authority (CA) signed SSL certificate.The use of the expensive SSL certificates with huge address bar banner speaks differently about the service than the simple green padlock does:
Send Your Emails
Your email services will not be affected by the status and reputation of the shared IP address because all your email will be send from your dedicated IP address.
Of course solely the usage of dedicated IP will not immunize you against spam accusations but since the end result depends solely on you if you are following the best email marketing practices there is nothing to worry about.
One very popular anti-spam practice is to reject email sent from domain without PTR record which converts the IP address into a domain name (exactly the opposite of what DNS A record does):
If you have multiple domains in your dedicated hosting you must select the most valuable one for your email marketing and create the PTR record for this domain.
cPanel does not provide interface to create a PTR record and if you need one you must contact the support department to create it.
Dedicated IP Common Misconceptions
Will a dedicated IP address make my site faster? No.
Will a dedicated IP address help my Google ranking? No. Run away from people ('experts') who claim the opposite
Will a dedicated IP address help with search engine optimization (SEO)? No. Run, Forrest, Run ... (A famous quot from the movie 'Forrest Gump'.)