I have a Cisco ASA with an inside, outside, and guest interfaces. On the guest interface I have installed a Cisco Wireless Controller for our wireless network. On the guest interface on the ASA it has access to a vlan that some of the servers are on (inside) and a vlan that the users are on. A couple of my DNS servers that are on the server vlan (inside) are on the guest interface as well.
So employee users and guests can logon to the wireless network (employees logon to "Company Wireless" integrated AD user account and guests logon to wireless "Company Guest" and have access our intranet on the internal server and a few other resouces. Everything works fine. Employees receive 10.1.20.X IP and guestes receive 10.1.254.X (whic is the subnet of the guest wireless network as well).
However, on the Cisco Wireless Controler that is on the guest interface, in the DHCP settings for DNS server I put google DNS 188.8.131.52 and 184.108.40.206. Guests can access the internet no problem but cannot access the intranet and other network resources using FQDN. If I put the IP address for those resources it works fine. If I put my internal DNS IP address in the DHCP scope it works fine.
How come Google DNS cannot resolve the FQDN of my network resources?
Also, the internal network resources are intranet.domain.com (and a few others) have internal and external DNS records so they should be able to be resolved by Google DNS.