Prepend nameserver to resolv.conf in Ubuntu 19.10

Question

I'm trying to add a nameserver to the top of my resolv.conf file on Ubuntu 19.10. I want to always have the nameserver 127.0.0.1 at the top.

I have created a created a new file called:

/etc/NetworkManager/conf.d/10-dhcp.conf

and in that file I have added:

[main]
dhcp=dhclient

And that kinda worked when rebooting the computer, however when the laptop goes to sleep the resolv.conf file no longer has my custom name sever prepended to the top of the file. What is the best way to get this change to stick in Ubuntu 19.10?

My /etc/systemd/resolved.conf file looks like this:

[Resolve]
DNS=127.0.0.1
#FallbackDNS=
#Domains=
#LLMNR=no
#MulticastDNS=no
#DNSSEC=no
#DNSOverTLS=no
#Cache=yes
DNSStubListener=no
#ReadEtcHosts=yes

My /etc/resolv.conf file looks like this:

nameserver 127.0.0.53
options edns0
search lan

And the permissions on my /etc/resolv.conf file look like this:

lrwxrwxrwx 1 root root 39 Dec 6 08:09 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

Output of systemd-resolv --status

 > systemd-resolve --status
Global
       LLMNR setting: no
MulticastDNS setting: no
  DNSOverTLS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
  Current DNS Server: 127.0.0.1
         DNS Servers: 127.0.0.1
          DNSSEC NTA: 10.in-addr.arpa
                      16.172.in-addr.arpa
                      168.192.in-addr.arpa
                      17.172.in-addr.arpa
                      18.172.in-addr.arpa
                      19.172.in-addr.arpa
                      20.172.in-addr.arpa
                      21.172.in-addr.arpa
                      22.172.in-addr.arpa
                      23.172.in-addr.arpa
                      24.172.in-addr.arpa
                      25.172.in-addr.arpa
                      26.172.in-addr.arpa
                      27.172.in-addr.arpa
                      28.172.in-addr.arpa

Answer 1

Remove /etc/NetworkManager/conf.d/10-dhcp.conf.

Edit /etc/systemd/resolved.conf and change:

sudo -H gedit /etc/systemd/resolved.conf # edit file

This:

[Resolve]
#DNS=
#FallbackDNS=
#Domains=
#LLMNR=no
#MulticastDNS=no
#DNSSEC=no
#DNSOverTLS=no
#Cache=yes
#DNSStubListener=yes
#ReadEtcHosts=yes

To this:

[Resolve]
DNS=127.0.0.1
#FallbackDNS=
#Domains=
#LLMNR=no
#MulticastDNS=no
#DNSSEC=no
#DNSOverTLS=no
#Cache=yes
DNSStubListener=no
#ReadEtcHosts=yes

reboot # reboot computer

systemd-resolv --status # check DNS servers

Correctly now shows 127.0.0.1 as the default DNS servers, so it should now work with your dnsmasq installation.