Addon domain is a fully functional domain that can be hosted from your web hosting control panel. An Addon domain can be created by following steps:
1. Log into your Domain Control panel and change the Nameserver to the nameserver of the server in which you wish to create it as an addon- domain.
2. Then log in to your Control panel and click on Addon Domains:
3. Then give domain in the New Domain Name field and the rest of the columns will be automatically filled(subdomain and Document root).
4. Then check the box, if you want FTP account for the domain and click on Add Domain Button.
If your nameserver of the domain is wrong, You can see the error:
That's All!