Since security related to Dynamic updates in Bind is currently only 
IP-related and not username and password there are a few things to look
out for.

Every user on the system will have access to update the zones managed 
with DnsZone, so you need to either trust these users enough or simply 
use a machine only to run DnsZone on.

IP-spoofing:
Should not be a problem, since routers should take care of removing 
packets that are trying to be spoofed as coming from the local network. 
IP spoofing from the local lan could be a possibility but generally you
would trust machines on your local lan.

If you don't trust machines on your local lan you can setup a local 
network between your DnsZone frontend and the nameserver you want to do
updates in.
