Netplan DNS disaster

I'm struggling to get netplan to work. (I thought I still wanted resolv.conf this does fix DNS but gets re-written on reboot.) Everything appears to be correct but I can't ping.

$ sudo netplan --debug apply
** (generate:14256): DEBUG: 00:38:22.887: Processing input file /etc/netplan/50-cloud-init.yaml..
** (generate:14256): DEBUG: 00:38:22.888: starting new processing pass
** (generate:14256): DEBUG: 00:38:22.888: We have some netdefs, pass them through a final round of validation
** (generate:14256): DEBUG: 00:38:22.888: ens160: setting default backend to 1
** (generate:14256): DEBUG: 00:38:22.888: Configuration is valid
** (generate:14256): DEBUG: 00:38:22.888: Generating output files..
** (generate:14256): DEBUG: 00:38:22.888: NetworkManager: definition ens160 is not for us (backend 1)
DEBUG:netplan generated networkd configuration changed, restarting networkd
DEBUG:no netplan generated NM configuration exists
DEBUG:ens160 not found in {}
DEBUG:Merged config:
network:
  bonds: {}
  bridges: {}
  ethernets:
    ens160:
      critical: true
      dhcp4: true
      dhcp4-overrides:
        use-dns: false
      dhcp6: true
      dhcp6-overrides:
        use-dns: false
      ipv6-privacy: true
      nameservers:
        addresses:
        - 10.10.11.200
        - 1.1.1.1
        search:
        - home
  vlans: {}
  wifis: {}

DEBUG:Skipping non-physical interface: lo
DEBUG:device ens160 operstate is up, not changing
DEBUG:Skipping non-physical interface: docker0
DEBUG:Skipping non-physical interface: hassio
DEBUG:Skipping non-physical interface: vethecdde1c
DEBUG:{}
DEBUG:netplan triggering .link rules for lo
DEBUG:netplan triggering .link rules for ens160
DEBUG:netplan triggering .link rules for docker0
DEBUG:netplan triggering .link rules for hassio
DEBUG:netplan triggering .link rules for vethecdde1c
$ ping google.com
ping: google.com: Temporary failure in name resolution

edits per request.

I assumed I was using netplan since it was installed.

/etc/netplan/50-cloud-init.yaml I did not create this file it was there.

network:
    ethernets:
        ens160:
            critical: true
            dhcp4: true
            dhcp4-overrides:
                use-dns: false
            dhcp6: true
            dhcp6-overrides:
                use-dns: false
            ipv6-privacy: true
            nameservers:
                search: [home]
                addresses: [10.10.11.200, 1.1.1.1]

    version: 2

When I try to the two commands I get error for both.

$ sudo systemd-resolve --status
Failed to get global data: Unit dbus-org.freedesktop.resolve1.service not found.
$ sudo resolvectl --status
sudo: resolvectl: command not found

What you want is Dnsmasq. Netplan only allows to configure fallback DNS, not a domain DNS.

Prepare installation

• Remove "systemd-resolved"
  • sudo systemctl disable systemd-resolved
  • sudo systemctl stop systemd-resolved
• Remove linked resolv.conf
  • Make sure it is a link (will point to something like: ...systemd/resolve/stub-resolv.conf):
  • sudo ls -lh /etc/resolv.conf
  • Remove link:
  • sudo rm /etc/resolv.conf
• Add temporary DNS
  • sudo echo "nameserver 8.8.8.8" > /etc/resolv.conf
• Install Dnsmasq
  • sudo apt update
  • sudo apt install dnsmasq

Problem with dnsmasq.d/lxd

You might get this error when dnsmasq starts initially:

dnsmasq: cannot access /etc/dnsmasq.d/lxd: No such file or directory

To resolve this just remove symlink ¯\(ツ)/¯

sudo rm /etc/dnsmasq.d/lxd

And restart:

service dnsmasq restart
service dnsmasq status

Configure DNSmasq

Edit /etc/dnsmasq.conf.

Search and uncomment this options:

• domain-needed
• bogus-priv
• strict-order
• no-resolv

Add your domain DNS servers e.g.:

server=/mycompany.com.pl/192.168.0.123
server=/some.vlan/10.234.0.123

Add generic servers e.g.:

server=1.1.1.1
server=8.8.4.4

Restart when done:

service dnsmasq restart
service dnsmasq status

Note that status will show which DNS servers are actually used (using nameserver ...).

Final steps

• Set DNS to local:
  • Add local DNS in resolve:
    • sudo echo "nameserver 127.0.0.1" > /etc/resolv.conf
  • Update /etc/netplan/ yaml file too.
• Test with dig (or ping).
  • (look for ;; ANSWER SECTION:)
  • dig app01.some.vlan
  • dig server.mycompany.com.pl
• Enable running on boot:
  • systemctl enable dnsmasq