Is there a method, maybe using .htaccess and PHP, to have the example.com/mobile appear in the browser as mobile.example.com?
I got this from the DNS administrator:
I didn’t say that “the IPs should not be unique”, but I said that “the IP addresses must not be unique”. There is a difference between “should” and “might”. I’ve already explained your colleague that the current IP address can be used for your subdomains. But in that case, your web server must be properly configured. It must support the virtual hosts. This functionality has to do nothing with DNS (“A or CNAME records”).
You can ask your web developer or a system administrator about it.
I’m not certain if DH supports vhosts… I haven’t been able to find if they do or documentation on how to manage them.