apt-cache show resolvconf
in the old days if you wanted to set your DNS servers on Linux you edit
echo "nameserver 192.168.3.45
search example.com" | sudo resolvconf -a eth0.inet
if you want the changes to take effect immediately without rebooting or ifdown/ifup the interface.
This is ass backwards. I remember the old days when we used to make fun of Windows for having to reboot after changing DNS server settings. Here you have a modern Linux OS that basically requires you to reboot, down your interface, or type a dumb string of commands consiting of echo and pipes. Ridiculous. While i'm not a fan of systemd I hope this shit gets fixed and simplifed with the advent systemd