[ale] Multi-label names

[Todor Fassl]

Old resolv.conf:
--- begin ---
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by 
resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 192.168.0.1
search example.com
--- end ---

New resolv.conf:
--- begin ---
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual 
nameservers.
nameserver 127.0.0.53
search example.com
--- end ---

Stopping systemd.resolvd makes host lookups fail entirely as you would 
expect from the above resolve.conf. If nothing is listening on 127.0.53, 
host lookups are going to fail. The problem is clearly with the switch 
from resolvconf (xenial) to systemd.resolvd (artful). However, like I 
said, I cannot make sense of the man page except for one thing. It says 
you can put stuff in /etc/systemd/resolv.conf that you'd put in any 
other resolv.conf. But there is nothing in there now, just comments. 
Clearly, systemd.resolvd is getting the name server and search domain 
from DHCP as it should. But it's behaviour is slightly different than 
resolvconf. I don't have any zesty machines around to see when the 
problem began but I think it started with artful.

I suppose you're going to ask for the results of that command in the new 
resolv.conf.

$ systemd-resolve --status
Global
          DNS Servers: 192.168.0.1
           DNS Domain: example.com
           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 (eno1)
       Current Scopes: LLMNR/IPv4 LLMNR/IPv6
        LLMNR setting: yes
MulticastDNS setting: no
       DNSSEC setting: no
     DNSSEC supported: no


On 03/07/2018 12:28 PM, Lightner, Jeffrey wrote:> Does it run any better 
if you turn off systemd-resolv (systemctl stop systemd-resolv)?
 >
 > What is in your /etc/resolv.conf on the two servers?
 >
 >
 >
 > -----Original Message-----
 > From: Ale [mailto:ale-bounces at ale.org] On Behalf Of Todor Fassl via Ale
 > Sent: Wednesday, March 07, 2018 1:09 PM
 > To: Atlanta Linux Enthusiasts
 > Subject: [ale] Multi-label names
 >
 > I am having a problem after an upgrade to ubuntu artful. If I do a 
host lookup for a non-existing, unqualified host name, it takes a long 
time to error ot. Say I have a host named spock. I can say, "host spock" 
and that comes back instantly. If I say, "host sopck" or some other 
typo, it takes like 10 seconds and I get this:
 > $ host -v sopck
 > Trying "sopck.example.com
 > Trying "sopck"
 > ;; connection timed out; no servers could be reached
 >
 > On an old machine, I get this:
 > $ host -v sopck
 > Trying "sopck.example.com
 > Trying "sopck"
 > Host sopck not found: 3(NXDOMAIN)
 > Received 98 bytes from 192.168.0.1#53 in 0 ms
 >
 > I see that on the ubuntu/artful machines, I am running systemd-resolv 
(through no fault of my own). It's listening on 127.0.0.1 and caching 
DNS queries. So trying to read the man page for systemd-resolv, I keep 
coming across the term "multi label names". I never heard that term 
before, don't know what it means, and it appears to be ungoogleable.
 >
 > Any advice on the original problem or on the meaning of that term 
would be appreciated.
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 >
-- 
Todd