Comment by jessaustin | Hacker News Reader

Comment by jessaustin | Hacker News Reader

After updating to 18.04, local DNS no longer works on this machine. It worked before. It seems that the systemd "stub" resolver isn't failing over to the LAN DNS server specified by DHCP. resolve.conf is just a single reference to systemd-resolved. It seems systemd-resolved knows about the LAN DNS server:

  $ systemd-resolve --status | head -4
  Global
         DNS Servers: 192.168.88.1
                      <ISP IP 1>
                      <ISP IP 2>

It's not using it though:

  $ nslookup laser
  Server:         127.0.0.53
  Address:        127.0.0.53#53

  ** server can't find laser: SERVFAIL

  $ nslookup laser 192.168.88.1
  Server:         192.168.88.1
  Address:        192.168.88.1#53

  Non-authoritative answer:
  Name:   laser
  Address: 192.168.88.5

Not clear to me whether this is a problem with systemd or with ubuntu integration of systemd. Glancing at /var/log/syslog, it seems systemd-resolved is restarting every four minutes, which seems unnecessary.

This is "by design"[0], though you should have seen it crop up in 17.04 when it became the default. I was bitten by it too and disabled systemd-resolved.

0: https://github.com/systemd/systemd/issues/6224#issuecomment-...

Thank you so much! This box came from the vendor on 16.04 and never ran on 17.04.

Of course, setting the following in /etc/systemd/resolved.conf did no good:

  LLMNR=no

...because apparently systemd-resolved just ignores its configuration. (I did restart the service; it made no difference.) I re-commented that setting since it does nothing. In order to get this working, I instead had to change the symlink /etc/resolv.conf which previously pointed to /run/resolvconf/resolv.conf to instead point to /run/systemd/resolve/resolv.conf, another dynamic file which is also maintained by systemd-resolved.

So now I have systemd-resolved handling the info from the DHCP ack, but it isn't handling DNS. This works, but good grief.

It's one of many questionable design decisions in the systemd project, in my view. The other one that I really dislike is the entire logging system moving away from plain text files toward binary journals and complex commands to view them.

I'm fairly neutral on having systemd handle DNS. It seems unnecessary, but I'm not an OS dev. I do strongly prefer text logs, which are still in use on the system under discussion.

Really infuriating since it means I no longer can lookup A records on TLD's. Breaking an old DNS feature...

    $ nslookup dk.
    Server:		127.0.0.53
    SERVFAIL
    $ nslookup dk. 8.8.8.8
    Server:		8.8.8.8
    Non-authoritative answer:
    Name:	dk
    Address: 193.163.102.58

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