Ubuntu DNS Issues

Question

Using Ubuntu 18.04 - My DNS suddenly stopped working. Just had installed Docker and minikube etc - not sure if this caused it - no idea.

I can ping an IP (like Google) but cannot ping google.com.

$ ping google.com ping: google.com: Temporary failure in name resolution

$ nslookup google.com ;; connection timed out; no servers could be reached

Tried a couple of things

$ sudo rm /etc/resolv.conf
$ sudo ln -s /run/resolvconf/resolv.conf /etc/resolv.conf
$ sudo systemctl restart resolvconf

  Failed to restart resolvconf.service: Unit resolvconf.service not found.

$ sudo systemctl stop networking`
Failed to stop networking.service: Unit networking.service not loaded

Tried (re)install resolve.conf - did not work

sudo apt install resolvconf 
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?


sudo apt install resolvconf --fix-missing
E: Internal Error, ordering was unable to handle the media swap

Thanks

Answer 1

DNS in Ubuntu (and probably others) has gotten.. complicated.

First off, to get yourself back online in the short term, do the following:

sudo rm /etc/resolv.conf
echo 'nameserver 8.8.8.8' | sudo tee -a /etc/resolv.conf

This will point you directly at Google's DNS servers and bypass whatever is happening on your system.

Under normal circumstances (at least on 18.04 server edition) netplan.io, resolvconf, systemd-networkd, and systemd-resolved all have to be happy with each other for DNS to work. The first step would be to see if systemd-resolved is working. Does sudo systemd-resolve --status return the correct info? How about sudo systemctl status systemd-resolved? If systemd-resolved is running correctly, edit /etc/resolv.conf and point the nameserver at "127.0.0.53". Are things still working? Then resolvconf might be the culprit.