How do I configure a DNS server for Ubuntu Server 18.04 LTS?

It seems to me that every time a question is asked about the DNS of Ubuntu Server, there is too much fluff in the answers without any useful information. Therefore, I would like to request that people respond with a real solution and not with problems as the other threads have shown.

I am aware that Ubuntu 18.04 uses netplan for its network, and I have a file in /etc/netplan/50-cloud-init.yaml with the following information:

Image from /etc/netplan/50-cloud-init.yaml

I know that the syntax of this file is valid because when I do sudo netplan –debug, it does not respond with any syntax error. However, sudo netplan –debug apply
show this:

Image of sudo netplan –debug apply result

I have no idea what is happening and why Ubuntu decided to change this detestable system. However, I suspect DEBUG: the device enp0s10f0 operstate is unknown, no replugging is the problem here. Your advice would be appreciated. Thank you.