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

[Andreas Müller]

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@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"

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1899797

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Dan Streetman (ddstreet)]

as you indicated this is tied to your kernel version, i'm marking systemd as invalid.

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]