dhcpd and ddns: updating only certain dns servers

[Simon Hobson]

Christoph Kaegi wrote:

>We have separate sets of DNS servers for the inside and outside
>of our network.
>
>Currently, clients get their addresses from the dhcp server and
>get their names updated automatically on the internal nameservers.
>
>Now we would also like to dynamically update the external nameservers,
>but *only* with the names of those clients, that are visible from
>the internet. Clients that can't access the internet directly
>should not get their names published to the external nameservers.
>
>After all I've read I've not found a way to realize this with
>dhcpd-3.0.4. Can anyone acknowledge this or (much better:) tell
>me how this could be done?

It can't be done in a standard setup, and I'm not exactly sure if it 
can be done at all.

I think what most people do is to statically configure publically 
accessible devices (or at least use fixed addresses) and manually 
configure their DNS records. Since most people are using NAT, and 
even if they don't do NAT will have to configure a firewall to allow 
inbound connections, then this isn't normally an issue.