Update DNS settings

All DNS settings are stored in /etc/resolv.conf file, but it is not recommended to edit this file directly. Use resolvconf to manage DNS settings, first install resolvconf package:

apt update && apt upgrade
apt install -y resolvconf

There is a folder /etc/resolvconf/resolv.conf.d/ which contains base, head and tail files:

• head Any entry in head is prepended at the beginning of the resulting resolv.conf file
• tail Any entry in tail is appended at the end of the resulting resolv.conf file
• base used, when no other DNS configuration is available - can be used to set default DNS servers
• original is a backup of the original /etc/resolv.conf file at the time of installation of the resolvconf package

nano /etc/resolvconf/resolv.conf.d/head

Open /etc/resolvconf/resolv.conf.d/head with your favorite text editor and add the nameservers inside the opened file.

In the example we will add Cloudflare DNS servers:

nameserver 1.1.1.1
nameserver 1.0.0.1
nameserver 2606:4700:4700::1111
nameserver 2606:4700:4700::1001

or if you prefer Google DNS servers:

nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 2001:4860:4860:0:0:0:0:8888
nameserver 2001:4860:4860:0:0:0:0:8844

and save file and exit and update /etc/resolv.conf file:

resolvconf -u

Verify the change:

cat /etc/resolv.conf

Then you need restart networking and resolvconf services to apply changes:

service resolvconf restart
service networking restart

Disable systemd-resolved service

To prevent overwriting /etc/resolv.conf file by systemd-resolved service you should disable it. If you don’t do it, you will have to update /etc/resolv.conf file every time you reboot your system. And will change your DNS settings back to default (127.0.0.53):

systemctl disable systemd-resolved.service
reboot

You can also set immutable attribute to /etc/resolv.conf file to prevent overwriting it:

chattr -i /etc/resolv.conf

PS: Anytime your solution involves chattr, it’s not really a solution.