[Bug 1821491] Re: DNS lookup fails for local hosts

[Steve Roberts]

Thanks again Dan for taking the time to explain.

> stop using dig to debug your system.

Sorry thought I was using dig at your request...
I was originally using nslookup and ping to find out why I couldn't browse to the server on phspi05 (phspi05 is actually controlling the heating and cooling in my glasshouse)
and confusingly to me they give different results, ping often works when nslookup fails (as is currently the case on the desktop)

> you don't need the router configured to resolve the "single label" (without .phs) hostname ...
I have managed to telnet into the router:
# cat /etc/resolv.conf
domain phs
nameserver 208.67.222.222
nameserver 212.159.6.10

so clearly the domain is set, but if I remove the single label entry
from the router even ping fails from the desktop (but still works on the
laptop....) and it seems that when providing an address via dhcp (e.g.
to the laptop) the router puts both phs09 and phs09.phs in /etc/hosts,
so I guess the router needs it...

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https://bugs.launchpad.net/bugs/1821491

Title:
  DNS lookup fails for local hosts

Status in systemd package in Ubuntu:
  Invalid

Bug description:
  Mint 19 (Ubuntu Bionic) 
  Laptop so Using NetworkManager, and connecting wirelessly to LAN
  Upgraded from Mint 18.3 so using resolvconf...

  Versions:
  network-manager: 1.10.6-2ubuntu1.1
  resolvconf: 1.79ubuntu10.18.04.3 or 1.79ubuntu10.18.04.2
  systemd: 237-3ubuntu10.15

  dns is specified in NetworkMananager as 192.168.2.1
  the dns is a router, and has static ips assigned to certain hosts on my lan...

  $cat resolv.conf
  nameserver 127.0.0.53
  search phs
  options edns0

  $ nslookup phspi05
  Server:		127.0.0.53
  Address:	127.0.0.53#53

  ** server can't find phspi05: SERVFAIL

  If I explicity specify the dns:

  $ nslookup phspi05 192.168.2.1
  Server:		192.168.2.1
  Address:	192.168.2.1#53

  Non-authoritative answer:
  Name:	phspi05
  Address: 192.168.2.35

  I get the correct ip address...

  Same with dig...

  I would expect that the nameserver set in network-manager would be
  used....

  From tail of $ systemd-resolve --status

  Link 2 (wlp2s0)
        Current Scopes: DNS
         LLMNR setting: yes
  MulticastDNS setting: no
        DNSSEC setting: no
      DNSSEC supported: no
           DNS Servers: 192.168.2.1
            DNS Domain: phs

  So the dns address had been picked up from NetworkManager, but
  apparently is not being used...

  Thought it might be related to this bug:
  https://bugs.launchpad.net/ubuntu/bionic/+source/resolvconf/+bug/1817903

  So installed the proposed fix, but no change. I also tried removing
  package resolvconf, again no change...

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