[Bug 1899797] Re: dns does not resolve some names after updating kernel from 4.15.0-117 to a newer sub_version like -118 or -121

[Kai-Heng Feng]

** Also affects: linux (Ubuntu)
   Importance: Undecided
       Status: New

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Title:
  dns does not resolve some names after updating kernel from 4.15.0-117
  to a newer sub_version like -118 or -121

Status in linux package in Ubuntu:
  Incomplete
Status in systemd package in Ubuntu:
  New

Bug description:
  This morning i've got a kernel update. After that I could not send
  mails using thunderbird contacting my mail provider kontent.com.

  The last working system was: Linux server 4.15.0-117-generic
  #118-Ubuntu SMP Fri Sep 4 20:02:41 UTC 2020 x86_64 x86_64 x86_64
  GNU/Linux

  I tried 4.15.0-118 and 4.15.0-121 but using these I could not resolve:
  smtp.kontent.com - but I could resolve www.google.de.

  So it seems that using the newer kernels 118 and 121 I can not resolve
  some but not all addresses.

  I returned to kernel 4.15.0-117 and everything works fine again.

  systemd-resolve --status
  Global
           DNS Servers: 172.30.30.1    <--- this is an local router next to my "server"
            DNS Domain: ami.intranet
            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 2 (enp0s25)
        Current Scopes: DNS
         LLMNR setting: yes
  MulticastDNS setting: no
        DNSSEC setting: no
      DNSSEC supported: no
           DNS Servers: 172.30.30.1
            DNS Domain: ~.
                        ami.intranet
  andreas at server:~$ host smtp.kontent.com
  smtp.kontent.com has address 81.88.40.61

  doning the same with a newer kernel results in a "SERVERFAIL 2 error"

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