[Bug 1656830] Re: Ubuntu MATE 17.04: No DNS resolution caused by systemd-resolved

[Jaromir Obr]

I can see the same issue once I upgraded to Ubuntu 17.04 (previous Ubuntu 16.10 was not affected).
Sometimes when I resume my notebook from sleep, DNS stops working for a few minutes. Restart of network or systemd-resolved didn't help. It seems that it starts working once system turns DNSSEC mode off:

$ service systemd-resolved status
...

dub 17 13:53:38 mira-HP-ENVY-Notebook systemd-resolved[13838]: DNSSEC validation failed for question docs.google.com IN A: failed-auxiliary
dub 17 13:53:38 mira-HP-ENVY-Notebook systemd-resolved[13838]: DNSSEC validation failed for question docs.google.com IN AAAA: failed-auxiliary
dub 17 13:53:38 mira-HP-ENVY-Notebook systemd-resolved[13838]: DNSSEC validation failed for question www.googleapis.com IN A: failed-auxiliary
dub 17 13:53:39 mira-HP-ENVY-Notebook systemd-resolved[13838]: Using degraded feature set (UDP) for DNS server 10.0.0.138.
dub 17 13:53:39 mira-HP-ENVY-Notebook systemd-resolved[13838]: Server 10.0.0.138 does not support DNSSEC, downgrading to non-DNSSEC mode.

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Title:
  Ubuntu MATE 17.04: No DNS resolution caused by systemd-resolved

Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  This is something new in Ubuntu 17.04. Whenever I boot up or upon
  returning from sleep, I don't have DNS resolution available. What I
  have to do is go and shutdown systemd-resolved (sudo service systemd-
  resolved stop) and edit /etc/resolv.conf to point to 192.168.1.1 (my
  router) instead of 127.0.0.53. Then everything works peachy. Otherwise
  any DNS resolution attempt will result in SERVFAIL.

  Since this is a major issue out of the box and I don't see any other
  bug report on this yet, I wanted to report it. This happens both on my
  laptop and my desktop PC, so it's not something strange on a single
  machine, but since no one else is complaining about it yet, it may be
  related to my network configuration. My router forwards DNS requests
  to an ODROID C2 on the same subnet, which then does the DNS resolution
  via dnsmasq. Dnsqmasq is set up to forward the requests to multiple
  DNS servers and respond with whichever one was fastest.

  ProblemType: Bug
  DistroRelease: Ubuntu 17.04
  Package: systemd 232-8
  ProcVersionSignature: Ubuntu 4.9.0-11.12-generic 4.9.0
  Uname: Linux 4.9.0-11-generic x86_64
  ApportVersion: 2.20.4-0ubuntu1
  Architecture: amd64
  CurrentDesktop: MATE
  Date: Mon Jan 16 08:51:43 2017
  InstallationDate: Installed on 2017-01-08 (7 days ago)
  InstallationMedia: Ubuntu-MATE 17.04 "Zesty Zapus" - Alpha amd64 (20170107)
  MachineType: LENOVO 7675CTO
  PccardctlIdent:
   Socket 0:
     no product info available
  PccardctlStatus:
   Socket 0:
     no card
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.9.0-11-generic root=UUID=b64995c7-1fd6-405b-b7ee-de3e56fe0617 ro quiet splash zswap.enabled=1 vt.handoff=7
  SourcePackage: systemd
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 03/22/2011
  dmi.bios.vendor: LENOVO
  dmi.bios.version: 7NETC2WW (2.22 )
  dmi.board.name: 7675CTO
  dmi.board.vendor: LENOVO
  dmi.board.version: Not Available
  dmi.chassis.asset.tag: No Asset Information
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: Not Available
  dmi.modalias: dmi:bvnLENOVO:bvr7NETC2WW(2.22):bd03/22/2011:svnLENOVO:pn7675CTO:pvrThinkPadX61:rvnLENOVO:rn7675CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
  dmi.product.name: 7675CTO
  dmi.product.version: ThinkPad X61
  dmi.sys.vendor: LENOVO

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