Bdtyktl

My DNS server is 192.168.1.152.

This DNS is provided to clients by DHCP. The windows clients on my LAN resolve names properly using that DNS, but my Ubuntu VM doesn't.

The VM is set up with bridge networking and is being properly provided the DNS server, but my local hostnames aren't being resolved by nslookup or browsers.

Here is an nslookup of one of my local domains:

# nslookup unraid.local

Server:     127.0.0.53

Address:    127.0.0.53#53



** server can't find unraid.local: SERVFAIL

Here is what it should resolve by using my DNS server:

# nslookup unraid.local 192.168.1.152

Server:     192.168.1.152

Address:    192.168.1.152#53



Name:   unraid.local

Address: 192.168.1.152

/etc/resolv.conf has a wrong nameserver:

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)

#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN

# 127.0.0.53 is the systemd-resolved stub resolver.

# run "systemd-resolve --status" to see details about the actual nameservers.



nameserver 127.0.0.53

I ran that command. Under DNS Servers, confusingly, it specifies the correct server (and my default gateway).

root@ubuntu:~# 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 2 (ens33)

      Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6

       LLMNR setting: yes

MulticastDNS setting: no

      DNSSEC setting: no

    DNSSEC supported: no

         DNS Servers: 192.168.1.152

                      192.168.1.1

I don't want to "hard code" the DNS server's IP in a config file because I won't be able to resolve when I change networks.

How can I get resolvconf and NetworkManager to automatically set the DHCP server's IP in /etc/resolv.conf?

Try editing /etc/systemd/resolved.conf, adding your desired DNS server:

change this:

[Resolve]

#DNS=

to this (but use the one you want - this is an example):

[Resolve]

DNS=192.168.1.152

after that, restart the service:

service systemd-resolved restart

And when you check the status you should see

$ systemd-resolve --status

Global

         DNS Servers: 192.168.1.152



      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

Known systemd bug.

Temporary workaround with no need to reconfigure if the DNS IP's changes:

sudo rm -f /etc/resolv.conf

sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf

reboot

I finally got a solution for this problem for ubuntu 17.10. By default this version of Ubuntu uses systemd-resolved, which I hope is going to be stable for the next versions.

In order to use custom dns instead of the local systemd-resolved cache, do the following:

1. add new nameservers. Edit the file in /etc/systemd/resolved.conf as sudoer. Here I've commented out the DNS entry and placed my dns
   
[Resolve]
DNS=10.96.0.10 8.8.8.8 8.8.4.4





2. cancel the actual symlink to /etc/resolv.conf



3. create a new symlink sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf
   


4. restart the service sudo service systemd-resolved restart
   


5. restart the network manager sudo systemctl restart networking
   

And now if you dig to a name provided by your add dns, you should see the record resolved dig nexus.default.svc.cluster.mydomain

Last step is to update the order of resolution in /etc/nsswitch.conf, by placing the dns before the mdns4_minimal

hosts           files dns mdns4_minimal [NOTFOUND=return] resolve [!UNAVAIL=return] myhostname

I put together a script that works around the issue of Netplan not currently supporting the ability to supersede DHCP supplied DNS servers and domain search order. It creates the Netplan yaml file and configures systemd-resolved to work as expected.

################## Start Netplan config (renderer: NetworkManager)

#  Some useful commands for customisation

# NetConn=$(nmcli device show|grep GENERAL.CONNECTION|head -n1|awk '{print $2}')

# IP=$(nmcli device show|grep IP4.ADDRESS|head -n1|awk '{print $2}')

# GATEWAY=$(nmcli device show|grep IP4.GATEWAY|head -n1|awk '{print $2}')

# sed -i 's/renderer: networkd/renderer: NetworkManager/' //etc/netplan/01-netcfg.yaml

######################################

systemctl start NetworkManager

NIC=$(nmcli device show|grep GENERAL.DEVICE|head -n1|awk '{print $2}')



#####   create Netplan yaml config file

cat >/etc/netplan/01-netcfg.yaml <<EOF 

# This file describes the network interfaces available on your system

# For more information, see netplan(5).

  network:

   version: 2

   renderer: NetworkManager

   ethernets:

EOF

echo "    ${NIC}:" >> /etc/netplan/01-netcfg.yaml

cat >>/etc/netplan/01-netcfg.yaml <<EOF

      dhcp4: yes

      nameservers:

        search: [abc.domain.edu, def.domain.edu]

        addresses: [10.10.11.22, 10.10.11.23]



EOF



#work around DNS resolv bug

systemctl stop systemd-resolved

sed -i 's/#DNS=/DNS=10.10.11.22 10.10.11.23/' /etc/systemd/resolved.conf

sed -i 's/#Domains=/Domains=abc.domain.edu def.domain.edu' /etc/systemd/resolved.conf

systemctl start systemd-resolved

systemctl restart NetworkManager

netplan apply

reboot

############### End Netplan Config