I think i suffer from "tunnel vision" after spending the day on the first sections of LFS211 on networking, and i just want to confirm the obvious.
The old /etc/network/interfaces ha an effect if you don't use NetworkManager nor systemd-networkd.
What if by mistake you keep either of those services running while you go and create a configuration in /etc/network/interfaces?
Let's say, i have a NetworkManager connection profile for eth0 configured to use DHCP, but the /etc/network/interfaces has a static configuration.
What takes precedence?