[Bug 1733103] Re: DNS hostname resolution fails intermittently

[Dan Streetman]

Much has changed in systemd since 2017, please update this bug if this
still happens.

** Changed in: systemd (Ubuntu)
       Status: New => Invalid

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Title:
  DNS hostname resolution fails intermittently

Status in systemd package in Ubuntu:
  Invalid

Bug description:
  Since upgrading to 17.10, hostname resolution (via, e.g., Firefox or
  the "host" command-line tool) does not work reliably anymore.  Once
  hostname resolution fails (Firefox 57: "Hmm.  We're having trouble
  finding that site."), manually resolving the host via "systemd-
  resolve" succeeds and temporarily allows Firefox to also resolve that
  host.  After a few minutes, resolution of the same host fails again.

  Example with command-line "host" utility:

  $ host www.heise.de
  ;; connection timed out; no servers could be reached
  $ cat /etc/resolv.conf
  # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
  #     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
  # 127.0.0.53 is the systemd-resolved stub resolver.
  # run "systemd-resolve --status" to see details about the actual nameservers.

  nameserver 127.0.0.53
  search fritz.box
  $ systemd-resolve www.heise.de
  www.heise.de: 2a02:2e0:3fe:1001:7777:772e:2:85
                193.99.144.85

  -- Information acquired via protocol DNS in 273.2ms.
  -- Data is authenticated: no
  $ host www.heise.de
  www.heise.de has address 193.99.144.85
  www.heise.de has IPv6 address 2a02:2e0:3fe:1001:7777:772e:2:85
  $ systemd-resolve --status
  Global
           DNS Servers: 192.168.178.1
            DNS Domain: fritz.box
            DNSSEC NTA: 10.in-addr.arpa
                        16.172.in-addr.arpa
                        168.192.in-addr.arpa
                        17.172.in-addr.arpa
                        18.172.in-addr.arpa
                        19.172.in-addr.arpa
                        20.172.in-addr.arpa
                        21.172.in-addr.arpa
                        22.172.in-addr.arpa
                        23.172.in-addr.arpa
                        24.172.in-addr.arpa
                        25.172.in-addr.arpa
                        26.172.in-addr.arpa
                        27.172.in-addr.arpa
                        28.172.in-addr.arpa
                        29.172.in-addr.arpa
                        30.172.in-addr.arpa
                        31.172.in-addr.arpa
                        corp
                        d.f.ip6.arpa
                        home
                        internal
                        intranet
                        lan
                        local
                        private
                        test

  Link 4 (wlp3s0)
        Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
         LLMNR setting: yes
  MulticastDNS setting: no
        DNSSEC setting: no
      DNSSEC supported: no
           DNS Servers: fd00::cece:1eff:fe61:2ece

  Link 3 (enp0s20f0u5c2)
        Current Scopes: none
         LLMNR setting: yes
  MulticastDNS setting: no
        DNSSEC setting: no
      DNSSEC supported: no

  Link 2 (enp0s31f6)
        Current Scopes: none
         LLMNR setting: yes
  MulticastDNS setting: no
        DNSSEC setting: no
      DNSSEC supported: no

  [... wait 2-3 minutes ...]

  $ host www.heise.de
  ;; connection timed out; no servers could be reached
  $ systemd-resolve www.heise.de
  www.heise.de: 2a02:2e0:3fe:1001:7777:772e:2:85
                193.99.144.85

  -- Information acquired via protocol DNS in 284.2ms.
  -- Data is authenticated: no
  $ host www.heise.de
  www.heise.de has address 193.99.144.85
  www.heise.de has IPv6 address 2a02:2e0:3fe:1001:7777:772e:2:85

  ProblemType: Bug
  DistroRelease: Ubuntu 17.10
  Package: systemd 234-2ubuntu12.1
  ProcVersionSignature: Ubuntu 4.13.0-16.19-generic 4.13.4
  Uname: Linux 4.13.0-16-generic x86_64
  ApportVersion: 2.20.7-0ubuntu3.4
  Architecture: amd64
  CurrentDesktop: KDE
  Date: Sat Nov 18 19:32:56 2017
  InstallationDate: Installed on 2016-11-26 (357 days ago)
  InstallationMedia: Kubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.1)
  MachineType: LENOVO 20FXS05500
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.13.0-16-generic root=/dev/mapper/vgubuntu-root ro kopt=root=/dev/mapper/vgubuntu-root
  SourcePackage: systemd
  UpgradeStatus: Upgraded to artful on 2017-10-21 (28 days ago)
  dmi.bios.date: 09/04/2017
  dmi.bios.vendor: LENOVO
  dmi.bios.version: R07ET79W (2.19 )
  dmi.board.asset.tag: Not Available
  dmi.board.name: 20FXS05500
  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: None
  dmi.modalias: dmi:bvnLENOVO:bvrR07ET79W(2.19):bd09/04/2017:svnLENOVO:pn20FXS05500:pvrThinkPadT460p:rvnLENOVO:rn20FXS05500:rvrNotDefined:cvnLENOVO:ct10:cvrNone:
  dmi.product.family: ThinkPad T460p
  dmi.product.name: 20FXS05500
  dmi.product.version: ThinkPad T460p
  dmi.sys.vendor: LENOVO

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