[Bug 1650794] Re: Ubuntu server 17.04 fails dns on first boot

[DieterDrewanz]

XUbuntu 17.04 (and 16.04/16.10) fail to resolve DNS.

I did some investigations and figured out a little detail which may help
to solve issue.


A) Descrption:

With xubuntu 17.04 I cannot resolve dns-names. 
Fails with:
- ping
- firefox
- apt-get 
- and so on

This was working correctly:
nslookup  wwww.web.de

Error-Message:

$ ping google.com
ping: unknown host google.com

$ ping www.web.de 
ping: unknown host www.web.de

$ ping 8.8.8.8 
works well

DNS-resolving was mostly not working, Only short before updating and
once a short time again it was working. I used Lenovo Yoga 300 with
wlan.

B) Detected Detail of Difference

But I figured out, that it is depending on different wlan-router and
hot-spots.

systemd-resolve --status


No-DNS-Resolving-Problem:

Link 3 (wlp2s0)
      Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
       LLMNR setting: yes
MulticastDNS setting: no
      DNSSEC setting: allow-downgrade
    DNSSEC supported: no
         DNS Servers: 192.168.43.1

Link 2 (enp3s0)
      Current Scopes: none
       LLMNR setting: yes
MulticastDNS setting: no
      DNSSEC setting: allow-downgrade
    DNSSEC supported: yes
xubuntu at xubuntu:~$

With DNS Resolving Problem:

Link 3 (wlp2s0)
      Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
       LLMNR setting: yes
MulticastDNS setting: no
      DNSSEC setting: allow-downgrade
    DNSSEC supported: yes
         DNS Servers: 192.168.2.1
                      fe80::1
          DNS Domain: Speedport_W_724V_01011603_00_009

Link 2 (enp3s0)
      Current Scopes: none
       LLMNR setting: yes
MulticastDNS setting: no
      DNSSEC setting: allow-downgrade
    DNSSEC supported: yes


Link 3 (wlp2s0)
      Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
       LLMNR setting: yes
MulticastDNS setting: no
      DNSSEC setting: allow-downgrade
    DNSSEC supported: yes
         DNS Servers: 192.168.2.1
          DNS Domain: Speedport_W_724V_01011603_00_009

*******************************************
*  The difference I figured out was:          
*******************************************

    DNSSEC supported: no

    DNSSEC supported: yes

Hope this will help to solve the problem.

With 16.04 about two month ago I recognized similar problem on wired lan, too. 
But there dns resolving was not so long permanently broken for internet use.  
 

Perhaps dns-resolving is disturbed by trying some connections or
protocol-pieces with dnssec for secure-dns-https-checking or so on.

*************************************************************************


https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1663031


Appendix:     
Similar bugs posted in internet:
https://unix.stackexchange.com/questions/280264/no-dns-resolution-after-upgrade-from-ubuntu-14-04-to-16-04
https://askubuntu.com/questions/838948/16-10-fail-to-resolve-dns
https://askubuntu.com/questions/780689/why-does-dns-resolution-not-work-on-the-first-try
https://askubuntu.com/questions/622470/dns-probe-finished-bad-config-error-in-ubuntu-14-04/622493#622493
Old nearly similar bug:
https://askubuntu.com/questions/368435/how-do-i-fix-dns-resolving-which-doesnt-work-after-upgrading-to-ubuntu-13-10-s

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to ubuntu-meta in Ubuntu.
https://bugs.launchpad.net/bugs/1650794

Title:
  Ubuntu server 17.04 fails dns on first boot

Status in ubuntu-meta package in Ubuntu:
  Confirmed

Bug description:
  apt-get update fails after first boot when network interface is
  managed by ifup

  On a fresh install apt-get update fails:
  apt-get update
  …
  Could not resolve 'us.archive.ubuntu.com'

  ping also fails:
  ping -c1 -W1 us.archive.ubuntu.com
  ping: us.archive.ubuntu.com: Name or service not known

  but dig works:
  dig us.archive.ubuntu.com a +short
  91.189.91.23

  GETAROUND:
  - after each dhcp, do ifdown-ifup:
  sudo ifdown ens3; sudo ifup ens3

  ProblemType: Bug
  DistroRelease: Ubuntu 17.04
  Package: ubuntu-server 1.375
  ProcVersionSignature: Ubuntu 4.8.0-30.32-generic 4.8.6
  Uname: Linux 4.8.0-30-generic x86_64
  ApportVersion: 2.20.4-0ubuntu1
  Architecture: amd64
  Date: Sat Dec 17 11:28:41 2016
  InstallationDate: Installed on 2016-12-17 (0 days ago)
  InstallationMedia: Ubuntu-Server 17.04 "Zesty Zapus" - Alpha amd64 (20161217)
  ProcEnviron:
   TERM=screen
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: ubuntu-meta
  UpgradeStatus: No upgrade log present (probably fresh install)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/ubuntu-meta/+bug/1650794/+subscriptions