[ALUG] Any DNS/systemd experts here? I have a DNS problem on new xubuntu install

Chris Green cl at isbd.net
Sat Jun 3 17:37:07 BST 2017


My new laptop has xubuntu 17.04 installed and that runs
systemd-resolved for local DNS rather than the previous dnsmasq (run by
Network Manager).

I have a local server on my network that provides DHCP and DNS for the
systems on the LAN and thus I can find things by name. From all my
older (xubuntu 16.04) systems this works for both unqualified and
FQDNs:-

    chris$ host backup
    backup.zbmc.eu has address 192.168.1.101
    chris$ host pi
    pi.zbmc.eu has address 192.168.1.2
    chris$ host backup.zbmc.eu
    backup.zbmc.eu has address 192.168.1.101
    chris$ host pi.zbmc.eu
    pi.zbmc.eu has address 192.168.1.2
    chris$ 


However, from the xubuntu 17.04 system, it doesn't work for
unqualified names:-

    chris at t470$ host pi
    Host pi not found: 2(SERVFAIL)
    chris at t470$ host backup
    Host backup not found: 2(SERVFAIL)
    chris at t470$ host backup.zbmc.eu
    backup.zbmc.eu has address 192.168.1.101


It looks like it should work because systemd-resolve's configuration
seems right:-

chris at t470$ systemd-resolve --status
Global
          DNS Domain: zbmc.eu
          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 3 (wlp4s0)
      Current Scopes: DNS
       LLMNR setting: yes
MulticastDNS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
         DNS Servers: 192.168.1.2
                      8.8.8.8
          DNS Domain: zbmc.eu

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



Hey!  I think I see the problem, I set LLMNR to 'no' in the
configuration but above it's still 'yes'.  Why isn't it no? :-

    root at t470:/etc/systemd# more /etc/systemd/resolved.conf
    #  This file is part of systemd.
    #
    #  systemd is free software; you can redistribute it and/or modify it
    #  under the terms of the GNU Lesser General Public License as
    published by
    #  the Free Software Foundation; either version 2.1 of the License, or
    #  (at your option) any later version.
    #
    # Entries in this file show the compile time defaults.
    # You can change settings by editing this file.
    # Defaults can be restored by simply deleting this file.
    #
    # See resolved.conf(5) for details

    [Resolve]
    #DNS=
    #FallbackDNS=8.8.8.8 8.8.4.4 2001:4860:4860::8888 2001:4860:4860::8844
    Domains=zbmc.eu
    LLMNR=no
    #DNSSEC=no
    #Cache=yes
    #DNSStubListener=udp
    root at t470:/etc/systemd# 


... and I have restarted the service.  Help!


-- 
Chris Green



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