I installed 4 Ubuntu VMs on my laptop and added for each of them extra network adapter with static ips for private network. I configured one of them to be the internal DNS server, added his IP to the resolvconf base file for each of the VMs and restarted the resolvconf and the networking services.
In the resolv.conf file I saw 2 DNS servers:
my home router (I didn't add it in the resolvconf file)
the one I added.
For some reason my internal DNS (the second in the resolv.conf file) does not work.
I didnt add in the dhcp.conf and interface file anything.
What is generating the router DNS IP to the file and why it is doesnt work if the internal DNS is second? (it is working if I manually switch between them)