How to register an Apple computer's DNS record? (Equivalent to Windows "Register this connection's addresses in DNS")

Hi,

I've been racking my brain with this issue:

-I'm trying to figure out how to register a workstation to DNS servers while using a specific (reserved) IPv4 address.

-I put the network IPv4 settings to "Using DHCP with manual address", but as soon as I press Apply, this computer has its DNS record erased.

-I found online that this command in Terminal can register it back to the DNS servers: dsconfigad -restrictDDNS en0 (as std or local admin account) but to no avail.

-I've tried to rebind it to AD (just in case), but the DNS record still disappears after using a manual IP.

-The computer cannot be resolved but is still (of course) remotely accessible using the IP address.

Any help would be greatly appreciated.

Thanks!