How to set up with cacheing DNS for local network?

Question

Our new Lion Server has a static IP Address pointed to over the internet by our registrar's zone file. Planning the Lion Server installation process with the intent of hosting Web, Mail and Open Directory services to a small number of users who are nearly all located off-site. I do also want Lion Server to be a caching DNS Server and DHCP authority on the local network to replace what dnsmasq does on our current Linux server.
I am looking forward to offloading some of the lower level Linux administration tasks and putting myself in the hands of the Lion Server Setup Assistant and Server App :-) but at the same time don't understand some of  its assumptions and fear having to spend a lot of time experimenting and re-installing.
So, specifically, I want the Server App to know that my Lion Server has a "Host Name for the Internet" but that the DNS it sets up will not be the DNS for my zone - I will be managing that through my registrar's interfaces.
Second problem is my fnot understanding what name space devices on the local network will / should use. e.g.  The Linux server will be available for backups etc  on the local intranet (and optionally have a static ip address on the Internet) but MacBooks, PCs, iPads and iPhones will be served ip addresses by the Lion Server's DHCP. So will / should these dynamic devices have their machine names fully qualified by our domain name with RFC 1918 style ip addresses or something like .local?  How do I tell this to Lion's Server App / Setup Assistant? How easy is it to update these initial settings later?

Answer 1

You do indeed need to have a master zone on lion server.  There's no way to get around that since Open Directory depends on Kerberos and Kerberos depends on the DNS.  LS scripts may see that the rDNS record exists, but I highly doubt that it'll auto configure everything for you... and given the number of possible variables, I bet that even if it worked something would need additional tweaking.
Sounds like an interesting lab excersize.  You should try it on a test server!
Again... you just need to folow the set up procedure that Lion Server presents you with. 
It won't be smart enough to see your external records and use them to configure a key distribution center for your OD. 
As far as your caching needs...  Could you set up your DHCP server to set the DNS server setting to show your internal server as the first hit, and your external as the second?  That way when the client requests a resolution it'll not get a hit on your local server but will from the external? 
The question then is how long will it wait for a response from the first server?  Or will the first server respond with "I don't know" sending the client immediately to the second.
The server set up that I have works similarly.  I have an internal master DNS that is replicated to a secondary.  The first DNS has an A record (community.server.com) that points to the INTERNAL ip address of the secondary server that's also running the web service.  The first server is running DHCP.  It tells the clients to use the first and second servers as it's DNS lookup. 
Now...  Externally, my registrar hosts an A record for community.server.com that points to the external IP address of my router which then forwards the request to the proper port on the internal network.
This way, the local clients internally look up and get a response locally when they go for community.server.com.  Externally, clients that look up community.server.com get the external connection to the router in my school.
Yikes...  I fear that this is as clear as mud!
-Graham