DNS and DHCP cooperation

[marco.borsatino at poste.it]

Hi to all. Sorry for my bad english.
A big (for me) problem with DNS and DHCP.
For auto-educational purposes, I'm trying to configure a little network using VirtualBox.
The situation is Ok for DNS, as I've correctly configured my only DNS server with 2 subnets, each with only 1 PC; all the clients can access the other client and my virtual server.
Later, I've successfully installed DHCP, both client and server.
But when I try to make the server programs (named and dhcpd) to cooperate, I get lost in the documentation (I'm using different sources), and the situation collapses.
My client, which has a new DHCP assigned address, correctly pings the other virtual PC in the network, but when I ping this client from my virtual server, I see that it doesn't recognise the correct address (still present in the zone file); it always tries to ping 212.48.8.140, which seems not to exist in the real world (or at least it seems not to be eachable from the real PC) nor, clearly, in my virtual little network.
Ok, I've made a mistake, normal. In fact, I haven't undestood how the DHCP server updates zone files in the DNS server both server programs are in the same virtual PC).
So I came back to static address for my client; both clients still ping the other, but my DNS server still tries to ping this misterious (for me) address.
I've deinstalled the BIND from ports, but nothing has changed.
So, two questions:
- Where can I find a document that explains how to use jointly the two servers (starting from a very basic point of view) how to use DNS and DHCP? When I read the documents I'v found on the Internet, they correctly start considering securities issues, but, for me, for now, that's not important; first I'd like to see them to work;
- what is the reason of the strange beaviour of my virtual DNS server? I've solved starting with a new virtual PC, but I'd like to understand.

Thank for your help.

Marco