systemd-resolved giving false negatives

[Hadmut Danisch]

Hi,
I was just debugging why so many of my virtual machines have so much trouble in getting DNS responses and found, that the dnsmasq on the host machine, which is the DNS resolver for all machines asks the three (!) name servers given in /etc/resolv.conf, which is the regular two DNS resolvers from the LAN and 127.0.0.53 where systemd-resolved is running.

So every time dnsmasq is asking this systemd-resolved (in about one in three queries) it happens often, not always, that systemd-resolved is giving false negatives.

I currently do not see why systemd should bring it's own DNS resolver at all, and even worse, force that into /etc/resolv.conf, causing lots of trouble with false replies.

That's just another chapter of the intrusive natur of systemd.

What the hell should such a third nameserver be good for?

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: systemd 231-9ubuntu3
ProcVersionSignature: Ubuntu 4.8.0-41.44-generic 4.8.17
Uname: Linux 4.8.0-41-generic x86_64
NonfreeKernelModules: zfs zunicode zcommon znvpair zavl
ApportVersion: 2.20.3-0ubuntu8.2
Architecture: amd64
CurrentDesktop: XFCE
Date: Tue Mar 28 12:06:13 2017
InstallationDate: Installed on 2016-04-22 (339 days ago)
InstallationMedia: Lubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 004: ID 0bda:0821 Realtek Semiconductor Corp.
 Bus 001 Device 003: ID 046d:c31d Logitech, Inc. Media Keyboard K200
 Bus 001 Device 002: ID 046d:c05b Logitech, Inc. M-U0004 810-001317 [B110 Optical USB Mouse]
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M.
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.8.0-41-generic root=UUID=d0b47754-d5ca-49ec-8190-92a24e58e373 ro rootflags=subvol=@ nosplash noplymouth nomodeset text
SourcePackage: systemd
UpgradeStatus: Upgraded to yakkety on 2016-10-17 (162 days ago)
dmi.bios.date: 03/16/2016
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: P1.50
dmi.board.name: N3150-NUC
dmi.board.vendor: ASRock
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP1.50:bd03/16/2016:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rnN3150-NUC:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.name: To Be Filled By O.E.M.
dmi.product.version: To Be Filled By O.E.M.
dmi.sys.vendor: To Be Filled By O.E.M.

[dino99 (9d9)]

This is an unsupported release now. Please think to install the next LTS 'Bionic 18.04'

http://cdimage.ubuntu.com/ubuntu-next/daily-live/current/
https://www.omgubuntu.co.uk/2018/02/ubuntu-18-04-minimal-install-option