I've got a domain for which the DNS I control, and is hosted on the internet. I also have a NAT'd internal network (192.168.0.0/24) which has internet access, and which I also control. On this internal network, I also have a DNS resolver. DNS software on both is PowerDNS.

What I want to be able to do is for the DNS resolver on the internal network to be able to add/change records of queries and results that come down from the authoritative server. For example, the authoritative server might have a single record for animal.example.com:

animal.example.com.    IN    AAAA    2001:140:283::1

However, I'd like it so that when internal clients do a dns lookup for animal.example.com, they might get back the following:

animal.example.com.    IN    AAAA    2001:140:283::1
animal.example.com.    IN    A       192.168.0.2

Obviously, I could set up the internal DNS server to pretend to be authoritative for example.com, but that would require a fair bit of effort to keep the main DNS server and the internal DNS server in sync for the records which are the same between both. If the internal DNS server could somehow be made a slave of the main DNS server, but also have the provision to add its own results in, that would be ideal.

Is this possible?