No not any domain will work, only a domain that is in your control, meaning you can add/remove A type records into the DNS server.
say your domain is blabla.com
Your DNS A record should look like
ruckuscontroller A where x is the IP from your ZD or vSZ/SZ/SCG
and in the DHCP server you have to add the dhcpoption domain name with blabla.com
Regards
Martin