The addon feature allows hosting multiple websites in one account. This is the story line: you have a webhost with a cPanel interface and you want to add the new domain that you have recently registered to your current hosting account. The first thing that should be noted is that this is possible if your web host allows it. In some hosting packages it is included, in others it should be paid separately for adding more domains to your host.
An addon domain is added as a subdomain of the primary domain and its files are stored in a folder inside the public_html folder.
To set up the addon domain, two separate set of actions should be taken. The host should be set up and the nameservers of the new domain on the website that has been used for registration should point toward the web host.
2. Click on the “Addon Domains” icon in the “Domains” menu.
3. Enter the name of the addon domain next to the “New Domain Name”.
Note: When you enter the domain name, cPanel automatically fills the “Subdomain/FTP Username” and also “Document Root” fields. If you have multiple domains with the same name but different suffixes (.com, .org, .net) you need to manually enter a unique name for the “Subdomain/FTP Username”, otherwise leave it as it is.
4. Enter the directory which will contain the new domain’s files in front of “Document Root”.
CPanel will make this folder. You do not need to create it manually.
5. Set a good, strong password!
6. Click “Add Domain” button.
As mentioned before, the new domain is basically a subdomain of your primary domain. So you can access it both as a subdomain and also as an individual domain (e.g. addondomain.com or addondomain.primarydomain.com).
You can upload the files by logging in through the FTP of your primary website (the new domain is just a folder in your public_html folder) or through its own FTP with the new username and password.
Login to that website and set the nameservers using the information that your webhost provided you when you bought your hosting package. There is no difference between the nameservers of your primary website and your addon websites.