I have just been looking into this and found a reference to dynamic DNS support on the dNSZone home page (I believe ZeroShell uses dNSZone as the LDAP back-end for BIND 9):
A number of people have asked for Dynamic DNS support, or how they can make their DHCP server do DNS updates. There is now a tool that allows a zone to be updated based on the ISC DHCP server’s lease database updates. The tool is dhcp2ldapd-1.1 and is a Perl script written by Travis Groth.
I would find it very useful. Would it be possible to add this to ZeroShell?