Site to Site VPN trying to use one DNS Server for internal domain

[exomic]

Hi,

I just set up a OpenVPN site to site tunnel between two houses.

Here's the topology:

Site A 10.10.0.0/24 Internal domain name used: 1.example.com
Site B 10.0.0.0/24 Internal domain name used: 2.example.com

I would like to find the best way to setup a DNS Resolver for both site domain. On the site host name is used like nas.1.example.com (Site A) and nas.2.example.com (site B).

I need to keep resolving the root domain 1.example.com and 2.example.com using google dns as it's my Dynamic DNS domain and the ip keep changing so using the domain override function would not work as it would include the root domain that isn't a static ip.

Any ideas?