cPanel basics: Understanding ADD-ON domains vs Main-Domains on Reseller Accounts

If you've been a Plesk user and recently moved to a cPanel managed system, you've realized the two control panels take a completely different approach.  One of the primary differences is the concept of ADD-ON domains in cPanel, which doesn't even exist in Plesk. 

In cPanel, when you create a cPanel user account for a user, it's inextricably bound to a domain, referred to by cPanel as the "Main Domain".   You can't have a main domain without a cpanel account, and you can't have a cpanel account without a main domain.  And each cpanel account can only have 1 main domain, not multiple ones.

Within a single "cPanel account - main domain", you can add ADD-ON domains.  An add-on domain is a fully functional domain, allowing unique email addresses on that domain, and a URL that's completely unique, for example, if I had:

main-domain: me.com
add-on domain: meplus.com

Visitors access me.com by way of: me.com or www.me.com.
Visitors would access meplus.com by way of: meplus.com and www.meplus.com.

I could create an email address for bob...
bob@me.com...

and it would not exist as bob@meplus.com.

I could then create a bob@meplus.com... and it, and bob@me.com would be two completely different email addresses/users. 

So in virtually every way, they are separate... except for two concepts.  They share resources (disk limits, etc) and the add-on domain's files are stored as part of the directory structure of the main-domain.  So for example, it might look something like this:

me.com stored at: /root/user-me/me.com/
meplus.com stored at: /root/user-me-files/me.com/meplus.com

This creates an unusual side-effect... meplus.com would ALSO be accessible as:

me.com/meplus.com

Again, this is because the add-on domain's files are stored within the phyiscal directory of the main-domain.  It's just the way cpanel is designed... and the "add-on domain" concept is unique to cPanel (as far as the author of this article knows).

It also means that you don't have a way to provide control panel access for just the add-on domain if you wanted to.  So if you're a webmaster hosting sites for multiple customers, you can't provide cPanel access to an add-on domain user without giving them your entire cpanel user account credentials, which would get them access to everything. 

Additionally, cpanel will also create a SUBDOMAIN tying together the addon domain, and the primary domain... in our example, that would be:

meplus.me.com

This is all part of cpanel's approach and concept for managing domains and add-on domains.  

So add-on domains work really well for hosting muliple sites where there's no need to give independent control panel access to a separate user for each domain (add-on domain)... and where you don't mind this "shared resources and directory structure" factor.

If you must have multiple domains separate, each with a separate cpanel user account, then you have two options:

1) purchase a separate single domain hosting plan for each domain.  Each will be set up with a cpanel user account paried with it's main-domain.

2) purchase a RESELLER account.  cPanel has a secondary type of user called a "reseller account", which gives you the ability to create your own cpanel user accounts (each with their own main-domain), and those cpanel user accounts will be assoicated with your "cpanel reseller account".  So it operates one level higher in the hierarchy, so to speak.  There's more details on how this works here:

http://knowledge.3essentials.com/web-hosting/article/783/cPanel-Basics-Reseller-accounts.html

and

http://knowledge.3essentials.com/web-hosting/article/784/cPanel-basics-creating-additional-accounts-via-WHM.html

Please feel free to contact our support team if you have further questions on these topics.