How to setup multiple DNS zones in a single domain

Question

We have a small charter school running a Mac Open Directory network on a single subnet with a single registered FQDN for its internal domain. We are about to open a second school within a wing of the same building which will also be on a Mac Open Directory domain, but since it is legally a separate school (just administered by the same staff) it needs to be on it's own subnet and have its own LDAP directory.
Is there a way to program DNS between the two schools so that DNS traffic can be routed between them without breaking the DNS and Open Directory/Kerberos realms of either? Both schools will share the same internal domain name. Is it as simple as creating two primary DNS zones on each other's nameservers, both using the same domain name but each having its own designated nameserver for that particular subnet?
For instance, the existing school is running DNS on server1.example.com within the 10.39.54.0/23 subnet. The second school will be running DNS on server2.example.com within the 10.39.56.0/23 subnet. Would I then simply create two primary zones within each subnet, one referring to its own with itself as the nameserver and one within the neighbor subnet referencing that subnet's server as the designated nameserver.
Or would I do this with each schools DNS servers searching through its own subnet as its primary zone with the neighbor zone being added as a secondary zone?
Thanks!

Answer 1

You have two options.
Use a DNS server with a single internal domain example.com and have (as you said) server1.example.com
If the two subnets are on separate networks either via a router or VLAN, then you could run a separate DHCP server on each and advertise the appropriate DNS server for that subnet.
Otherwise you could have a single DNS server and either single DHCP advertising that single DNS server and have both server1 and server2 in the single DNS zone, or a DHCP server in each subnet but still pointing to the same single DNS server.
Each of these two servers would be an Open Directory Master
Note: in DNS terminology a DNS 'zone' is the same thing as a Domain Name.
The second option which if you want to keep the two 'schools' completely separate is to do the following
Use a DNS server per subnet
Use a DHCP server per subnet
Use a different domain name per school e.g. school1.com and school2.com
Create a server record on each as appropriate e.g. server1.school1.com and server2.school2.com
You cannot have a single DNS server have two identical zones e.g. example.com and example.com as they are of course the same thing.
If the two schools will merge officially at some point it might be better to use the same domain name, if they are going to fully split then definiately it is going to be better to use two different domain names.