You can add a wildcard entry for your domain name via the WHM account. To access WHM, you would login via the following link: xxx.xx.xxx.x/whm
Where "xxx.xx.xxx.x" is the cloud or dedicated server's ip address. You need the root login information in order to access WHM.
1. Log into WHM as the root user.
2. Click Edit DNS Zone, under "DNS Functions" on the left-side menu.
3. Choose the zone you want to add a wildcard to, and click edit.
4. Then scroll down until you see "Add New Entries Below this Line".
5. Put a * in the first box.
6. Select A from the drop down.
7. Next put the IP in the box that is on the right of the "A" dropdown.
8. Click Save.
In most cases it is just easier to add a * subdomain via the cPanel interface for the domain in question. More information about this procedure can be found in the link below.
How can i add a wild card dns entry for my domain name in cpanel?