[Bug 1644330] Re: systemd-resolved assumes that /etc/hosts for one address family means it doesn't ask DNS for another

[Martin Pitt]

I cannot confirm that glibc's "dns" works like that -- it behaves the
same as resolved:

$ grep heise.de /etc/hosts
1.2.3.4 heise.de

$ grep hosts /etc/nsswitch.conf 
hosts:          files dns

$ getent ahosts heise.de | grep STREAM 
1.2.3.4         STREAM heise.de

If I drop the heise.de entry from /etc/hosts, I get an IPv6 address
again as expected:

$ getent ahosts heise.de | grep STREAM 
2a02:2e0:3fe:1001:302:: STREAM heise.de
193.99.144.80   STREAM 

This is all after "sudo systemctl stop systemd-resolved", so it's not
interfering at all. Can you try the above on your system, to make sure
it behaves the same?

** Changed in: systemd (Ubuntu)
       Status: Triaged => Incomplete

** Changed in: systemd (Ubuntu)
     Assignee: Martin Pitt (pitti) => (unassigned)

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https://bugs.launchpad.net/bugs/1644330

Title:
  systemd-resolved assumes that /etc/hosts for one address family means
  it doesn't ask DNS for another

Status in systemd package in Ubuntu:
  Incomplete

Bug description:
  I have an ipv4 entry for a key host on my network listed in
  /etc/hosts, for network recovery purposes.  This host also has ipv6
  connectivity; the ipv6 address is resolvable via DNS, but I do not
  have it in /etc/hosts.  Resolution of hostname should be independent
  for each address family.

  Two days ago (I don't know what changed to trigger this), I stopped
  being able to resolve the ipv6 address for this host.  I traced this
  down to systemd-resolved, returning a lookup failure for the nss
  request, because the ipv6 address is not listed in /etc/hosts.

  Removing resolve from /etc/nsswitch.conf restores the correct
  behavior.

  Removing the ipv4 entry for the host restores the correct behavior.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.10
  Package: systemd 231-9ubuntu1
  ProcVersionSignature: Ubuntu 4.8.0-27.29-generic 4.8.1
  Uname: Linux 4.8.0-27-generic x86_64
  ApportVersion: 2.20.3-0ubuntu8
  Architecture: amd64
  CurrentDesktop: Unity
  Date: Wed Nov 23 08:13:33 2016
  InstallationDate: Installed on 2010-09-24 (2252 days ago)
  InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.1)
  MachineType: LENOVO 2306CTO
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.8.0-27-generic.efi.signed root=/dev/mapper/hostname-root ro quiet splash vt.handoff=7
  SourcePackage: systemd
  UpgradeStatus: Upgraded to yakkety on 2016-10-28 (25 days ago)
  dmi.bios.date: 10/25/2013
  dmi.bios.vendor: LENOVO
  dmi.bios.version: G2ET97WW (2.57 )
  dmi.board.asset.tag: Not Available
  dmi.board.name: 2306CTO
  dmi.board.vendor: LENOVO
  dmi.board.version: Not Defined
  dmi.chassis.asset.tag: No Asset Information
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: Not Available
  dmi.modalias: dmi:bvnLENOVO:bvrG2ET97WW(2.57):bd10/25/2013:svnLENOVO:pn2306CTO:pvrThinkPadX230:rvnLENOVO:rn2306CTO:rvrNotDefined:cvnLENOVO:ct10:cvrNotAvailable:
  dmi.product.name: 2306CTO
  dmi.product.version: ThinkPad X230
  dmi.sys.vendor: LENOVO

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