If you are hosting a domain on the internet and have a host you would like to reach via an internal address instead of an external address then you can do this in UCS. Adding the entry to the GUI is an option but if importing a large zone then that is NOT an option and you will need to use udm.

To add a split horizon entry you will have to add a zone entry just like in the GUI but using udm instead. Naturally you can use this method to add a new DNS Zone as well.

udm dns/forward_zone create --set zone="host.domainname.tld." --set a="xx.xx.xx.xx" --set nameserver="ucsns.ucsdomain.ucstld."

Modifying an entry or zone is a bit different than creating the entry. You will be needing to use the DN of the zone entry to target it.

udm dns/forward_zone modify --dn zoneName=host.domainname.tld,dc=ucsdomain,dc=ucstld --append nameserver="ucsns2.ucsdomain.ucstld." --append nameserver="ucsns3.ucsdomain.ucstld."