Gfilui

The systemd's DNS lovated at 127.0.0.53 appears to be working except when I query for local machines by name. But if I query for them and specifically specify the local DNS server (my router) then I get the proper reply. But the config file says it is also using the router as the search address. Any thoughts?

I am running Ubuntu 18.04 on my Dell laptop.

Incorrect Results:

$ nslookup web1

Server: 127.0.0.53
Address: 127.0.0.53#53

** server can't find web1: SERVFAIL

Also Fails

$ nslookup -i wlp3s0 web1
nslookup: couldn't get address for 'web1': not found

Correct Results:

$ nslookup web1 192.168.1.1

Server: 192.168.1.1
Address: 192.168.1.1#53

Name: web1
Address: 192.168.1.107

Configuration Info systemd-resolve

$ systemd-resolve --status

Global
 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
 29.172.in-addr.arpa
 30.172.in-addr.arpa
 31.172.in-addr.arpa
 corp
 d.f.ip6.arpa
 home
 internal
 intranet
 lan
 local
 private
 test

Link 3 (wlp3s0)
 Current Scopes: DNS
 LLMNR setting: yes
MulticastDNS setting: no
 DNSSEC setting: no
 DNSSEC supported: no
 DNS Servers: 192.168.1.1
 DNS Domain: wp.comcast.net

Link 2 (enp2s0)
 Current Scopes: none
 LLMNR setting: yes
MulticastDNS setting: no
 DNSSEC setting: no
 DNSSEC supported: no

Configuration Info NetworkManager

$ cat /etc/NetworkManager/NetworkManager.conf
[main]
plugins=ifupdown,keyfile

[ifupdown]
managed=false

[device]
wifi.scan-rand-mac-address=no

So how do I get nslookup to return the correct answer? Link 3 appears to be the correct information (my wifi connection) and my DNS on the router is returning the correct answer but the local cache never tries to look up the address (or so it seems).

I found the fix that worked for me.

my resolv.conf file was pointing to the wrong place. This seems like a bug in Ubuntu as it happened on my laptop (the machine I first noticed this issue on) and on a fresh install of Ubuntu 18.04 Server.

The Default

$ ls -l /etc/resolv.conf

lrwxrwxrwx 1 root root 39 Apr 26 12:07 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

I deleted this and pointed to the correct file. After rebooting, this solved my issue. And I was even able to switch networks on my laptop and the DNS switched correctly. Of course when on external networks I can't resolve any of my local machines but that is expected. As soon as I switch back to my local network, all the local machines resolve correctly because my router is the DNS.

The Fix

$ sudo rm -f /etc/resolv.conf
$ sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf
$ ls -l /etc/resolv.conf

lrwxrwxrwx 1 root root 32 May 29 08:48 /etc/resolv.conf -> /run/systemd/resolve/resolv.conf

$ sudo reboot

After that, everything worked as I expected and 127.0.0.53 is no longer being used at all.

The Correct Results

$ nslookup web1

Server: 192.168.1.1
Address: 192.168.1.1#53

Name: web1
Address: 192.168.1.107

$ nslookup google.com

Server: 192.168.1.1
Address: 192.168.1.1#53

Non-authoritative answer:
Name: google.com
Address: 172.217.7.174
Name: google.com
Address: 2607:f8b0:4004:80e::200e