Use different DNS servers for guest network on AirPort Extreme/Express I have an AirPort Extreme and Express which provide a guest and a private wireless network. I also have a Mac server (192.168.1.10) running on the LAN. I want that server to be accessed only on the private wireless network.

I want the hostname of the Mac server to resolve to 192.168.1.10 on the private wireless network instead of resolving to my external IP address. This means that DHCP clients on the private network need to have 192.168.1.10 as the primary DNS server and 8.8.8.8 as the secondary DNS server. The clients on the guest network on the other hand need different DNS servers (eg. 8.8.8.8 and 8.8.4.4).

How can I configure these settings separately for the private and guest network on the AirPort Extreme and Express?
What you are suggesting will provide name resolution to the 192.168.1 subnet but has nothing to do with restricting access. 

The correct way to do what you want is to firewall the device, or have no routing between your subnets. 

If you do want to set up just the DNS settings then all you have to do is propagate them via DHCP. This means having two separate DHCP scopes, one with the google DNS servers, and one with your internal DNS server.