Ubuntu 18.04 systemd-resolve doesn't read the /etc/resolv.conf properly

using 18.10 I had a similar problem. I resolved my problem by modifying /etc/systemd/resolved.conf with the dns server and search domain information. this looks to be correct behavior, according to the man page,

The DNS servers contacted are determined from the global settings in /etc/systemd/resolved.conf, the per-link static settings in /etc/systemd/network/*.network files (in case systemd- networkd.service(8) is used), the per-link dynamic settings received over DHCP, and any DNS server information made available by other system services. See resolved.conf(5) and systemd.network(5) for details about systemd's own configuration files for DNS servers. To improve compatibility, /etc/resolv.conf is read in order to discover configured system DNS servers, but only if it is not a symlink to /run/systemd/resolve/stub-resolv.conf or /run/systemd/resolve/resolv.conf (see below).

my config looks like this, adjust to fit your environment,

1. 192.168.1.1 is your private dns

2. domain syntax is important, don't forget the trailing dot "."

   /etc/systemd/resolved.conf [Resolve] DNS=192.168.1.1 #FallbackDNS= Domains=blah.mydomain.com. blahblah.mydomain.com. #LLMNR=no #MulticastDNS=no #DNSSEC=no #DNSOverTLS=no #Cache=yes #DNSStubListener=yes

then restart the service

sudo systemctl restart systemd-resolved.service

verify service is running. syntax errors might cause issues that you can see here.

sudo systemctl status systemd-resolved.service

try to lookup a local domain

nslookup blah.mydomain.com

if that did not work, then verify the query does not time out. manually specify the dns server

nslookup blah.mydomain.com 192.168.1.1

resolved has a built-in query function which is helpful

% resolvectl query fedoraproject.org
fedoraproject.org: 2605:bc80:3010:600:dead:beef:cafe:fed9 -- link: enp5s0
                   2620:52:3:1:dead:beef:cafe:fed7 -- link: enp5s0
                   2610:28:3090:3001:dead:beef:cafe:fed3 -- link: enp5s0
                   2604:1580:fe00:0:dead:beef:cafe:fed1 -- link: enp5s0
                   2605:bc80:3010:600:dead:beef:cafe:feda -- link: enp5s0
                   2620:52:3:1:dead:beef:cafe:fed6 -- link: enp5s0
                   209.132.190.2               -- link: enp5s0
                   8.43.85.67                  -- link: enp5s0
                   38.145.60.21                -- link: enp5s0
                   67.219.144.68               -- link: enp5s0
                   140.211.169.196             -- link: enp5s0
                   140.211.169.206             -- link: enp5s0
                   152.19.134.142              -- link: enp5s0
                   38.145.60.20                -- link: enp5s0
                   152.19.134.198              -- link: enp5s0
                   8.43.85.73                  -- link: enp5s0

-- Information acquired via protocol DNS in 99.8ms.
-- Data is authenticated: no