This post explains for how to add dedicated IP to addon domain or sub-domain. Please follows step by steps.
Step 1: You will need to first add the domain to your cPanel account.
Step 3: Edit the virtual host file for addondomain located at: /var/cpanel/useradata/username/addondomain.maindoman.com
Edit the virtual host file for subdomain located at:
Step 3 ( A ): First you must locate the line with the current IP address and edit this to your desired dedicated IP address
Step 3 ( B ): Save your file without changing anything else.
Step 4: Now run /usr/local/cpanel/scripts/rebuildhttpdconf
Step 6: Select your desired domain name here and click edit.
Step 7: Update your A records now to the new IP address and click save.
That’s it! 🙂