[Bug 1729194] Re: Systemd-Resolvd Forgets to Resolv Request

[Christopher]

Some more troubleshooting, I've found that if I manually set my
nameserver to 127.0.0.53 systemd-resolver starts working again. However
everytime that a wifi network connects or disconnects, it switches back
to `127.0.0.1`

It does look like systemd-resolve only listens on that port too. :

`udp        0      0 127.0.0.53:53           0.0.0.0:*
858/systemd-resolve`

So what I need to find out is why network-manager isn't using the right
settings for systemd-resolve.

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Title:
  Systemd-Resolvd Forgets to Resolv Request

Status in systemd package in Ubuntu:
  New

Bug description:
  Systemd sometimes just doesn't resolve DNS queries and for the life of
  me I don't know why.

  So often when I'm switching between wifi networks I find that systemd-
  resolved in 17.10 complete fails to do it's job. Here's the example.
  I'm connected to the internet :

  ```
  chalbersma at nebraska [~] {Tue Oct 31 20:58:18}        
  > ping 8.8.8.8            
  PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.         
  64 bytes from 8.8.8.8: icmp_seq=1 ttl=53 time=196 ms 
  64 bytes from 8.8.8.8: icmp_seq=2 ttl=53 time=67.5 ms                                                     
  64 bytes from 8.8.8.8: icmp_seq=3 ttl=53 time=78.9 ms                                                     
  ^C                        
  --- 8.8.8.8 ping statistics ---                      
  3 packets transmitted, 3 received, 0% packet loss, time 1999ms                                            
  rtt min/avg/max/mdev = 67.534/114.169/196.025/58.068 ms
  ```

  But I can't seem to resolve domains:

  ```
  chalbersma at nebraska [~] {Tue Oct 31 20:59:17}        
  > nslookup google.com
  ;; connection timed out; no servers could be reached

  ```

  So I did a `systemd-resolver --status` to see if it's getting the
  right dns server. It is :

  ```
  Link 3 (wlp2s0)                                      
        Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6      
         LLMNR setting: yes                            
  MulticastDNS setting: no                             
        DNSSEC setting: no                             
      DNSSEC supported: no                             
           DNS Servers: 192.168.43.1                   
                        2001:4888:51:ff00:506:d::      
                        2001:4888:50:ff00:500:d::

  ```

  And it's actually up and working properly :

  ```
  chalbersma at nebraska [~] {Tue Oct 31 21:02:06}
  > nslookup google.com 192.168.43.1
  Server:         192.168.43.1
  Address:        192.168.43.1#53

  Non-authoritative answer:
  Name:   google.com
  Address: 172.217.11.78
  chalbersma at nebraska [~] {Tue Oct 31 21:03:16}
  > nslookup google.com 2001:4888:51:ff00:506:d::
  Server:         2001:4888:51:ff00:506:d::
  Address:        2001:4888:51:ff00:506:d::#53

  Non-authoritative answer:
  Name:   google.com
  Address: 172.217.11.78
  ```

  Systemd just can't figure out to make the request. I did try the
  common step of flushing the cache (with `--flush-cache`) restarting
  network-manager and systemd-resolverd service but nothing seems to be
  able to make systemd-resolverd function. Even a reboot doesn't always
  fix the issue; sometimes it persists.

  For debugging this is what's in my /etc/resolv.conf :

  ```  
  chalbersma at nebraska [~] {Tue Oct 31 21:09:15} 
  > cat /etc/resolv.conf                        
  # Generated by NetworkManager                 
  nameserver 127.0.1.1      
  ```

  As soon as I manually set the nameserver from my loopback to the
  actual dns server (bypassing systemd-resolvd) things start working
  again. Let me know what kind of tshooting data I'd need to grab to
  help display this issue.

  In order to restore networking I had to manually edit that file and
  change my dns to the external source.

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