name resolution stops working

[Wolf Rogner]

System: Ubuntu 17.10 beta
DNS server hosts an internal and an external domain (the internal is used for internal purposes).

Name resolution works for a while. Every now and then, the name resolution stops working.
This issue was reported in 17.04 but no suggestion for resolv has worked.

In 17.10 the symptoms are the same, the duration till it happens are longer (about 1.5 days).

restarting systemd-resolved solves the issue temporarily. However, this should not be required at all.

Happens on a fresh install

Setup:

DNS serves rsb.at and rsb.intern
Server www.rsb.at can be reached even when internal resolution fails.
Seems that the internal DNS server (the first in the line) is not queried first.
If so, an rsb.intern address will not be found.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: systemd 234-2ubuntu10
ProcVersionSignature: Ubuntu 4.13.0-11.12-generic 4.13.1
Uname: Linux 4.13.0-11-generic x86_64
ApportVersion: 2.20.7-0ubuntu1
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Fri Sep 22 11:05:57 2017
InstallationDate: Installed on 2017-09-05 (16 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Alpha amd64 (20170902)
Lsusb:
 Bus 002 Device 002: ID 05ac:8406 Apple, Inc.
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 003: ID 05ac:0273 Apple, Inc.
 Bus 001 Device 002: ID 05ac:8290 Apple, Inc.
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Apple Inc. MacBookPro12,1
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.13.0-11-generic root=/dev/mapper/ubuntu--vg-root ro quiet splash vt.handoff=7
SourcePackage: systemd
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/18/2017
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MBP121.88Z.0167.B33.1706181928
dmi.board.name: Mac-E43C1C25D4880AD6
dmi.board.vendor: Apple Inc.
dmi.board.version: MacBookPro12,1
dmi.chassis.type: 9
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-E43C1C25D4880AD6
dmi.modalias: dmi:bvnAppleInc.:bvrMBP121.88Z.0167.B33.1706181928:bd06/18/2017:svnAppleInc.:pnMacBookPro12,1:pvr1.0:rvnAppleInc.:rnMac-E43C1C25D4880AD6:rvrMacBookPro12,1:cvnAppleInc.:ct9:cvrMac-E43C1C25D4880AD6:
dmi.product.family: MacBook Pro
dmi.product.name: MacBookPro12,1
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
mtime.conffile..etc.systemd.resolved.conf: 2017-09-06T23:14:52.682864

[Wolf Rogner (war-rsb)]

Just found this article
https://github.com/systemd/systemd/issues/5755

Following the argument, systemd-resolved resolves DNS names on the assumption that all configured DNS servers are equal.

diego-treitos and others argue that in small/medium sized companies, DNS configuration will have an external DNS server configured and conveyed via DHCP.

This is the case here as well.

This has not posed a problem before systemd-resolved was adopted. But when a resolver insists on treating the fallback equally and keeping the connection till the next fallback, internal DNS resolution is not possible any more.

It breaks known and established configurations.

I have to accept that RFCs actually lend to the interpretation of poettering.

In this case (as he is reluctant to adapt his softwares behaviour to previously known standards) there need to be a quick way to eliminate systemd-resolver from the system.

I for one need the old behaviour with a primary DNS (internal, it resolved private addresses as well) and a secondary DNS (external, which only resolved external / official addresses) as a fallback.

[Wolf Rogner (war-rsb)]

To make clear the bearing of this:

systemd-resolved stops working on EVERY machine here after 5 minutes.

the DNS server has not been down since April

A Macintosh running macOS High Sierra installed for comparison can resolve and connect to internal resources in every case where Ubuntu looses connection.

And a last one: internally, my domain uses .internal as domain name. I want to keep this separate from my official domains.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Sebastien Bacher (seb128)]

thank you for your bug report. So the issue there is the same as in the upstream ticket, that you expect the lookups to always be done using the servers in the order of what is in resolv.conf? if so could you update the title to state that/what you believe the problem to be exactly?

[Dan Streetman (ddstreet)]

please reopen if this is still an issue