Systemd-resolved cannot forget local DNS Domain name after leaving the network

[Dmitry Lapshin]

At my university, WiFi network setup sets a local DNS Domain name (in a form of <university-name>.<country-tld>). That's alright; but when I come home with my laptop and resume it, the local DNS Domain name is still set (checked via systemd-resovle --status), and because of that I cannot open my university website: it's domain cannot be resoved on a local DNS (of course it cannot be resolved, it's not in local network anymore). Resolving manually on any other DNS server (via dig @<providers DNS or 1.1.1.1 or 8.8.8.8>) works perfectly fine. Resolving any non-local name works fine too. DNS resolver IP's are right. Restarting systemd-resolved or-and NetworkManager does not fix the issue, only the full reboot can help. That's pretty annoying.

I am running Ubuntu 17.10 (soon to be upgraded to 18.04). Have this issue since installing 17.10, but wasn't able to find a clue until today.

What should be happening: Well, after I leave the network, resolver should forget local settings from that network, right?

What is happeing: it does not. Well, at least the resolver ip's are right.

P.S. It might be a NetworkManager issue but the only thing that I find that remembers local DNS is the systemd-resolved, feel free to change package.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: systemd 234-2ubuntu12.3
ProcVersionSignature: Ubuntu 4.13.0-39.44-generic 4.13.16
Uname: Linux 4.13.0-39-generic x86_64
ApportVersion: 2.20.7-0ubuntu3.8
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sat Apr 28 18:26:01 2018
InstallationDate: Installed on 2016-04-23 (734 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
MachineType: ASUSTeK Computer Inc. U40Sd
ProcEnviron:
 LANG=ru_RU.UTF-8
 TERM=tmux-256color
 SHELL=/bin/bash
 XDG_RUNTIME_DIR=<set>
 PATH=(custom, user)
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.13.0-39-generic root=UUID=ea1ac96c-71bd-4b8e-81ad-24abb9a24ce0 ro nogpumanager quiet splash vt.handoff=7
SourcePackage: systemd
SystemdDelta:
 [EXTENDED] /lib/systemd/system/docker.service → /etc/systemd/system/docker.service.d/docker.conf
 [EXTENDED] /lib/systemd/system/rc-local.service → /lib/systemd/system/rc-local.service.d/debian.conf
 [EXTENDED] /lib/systemd/system/user@.service → /lib/systemd/system/user@.service.d/timeout.conf

 3 overridden configuration files found.
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/16/2011
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: U40Sd.202
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: U40Sd
dmi.board.vendor: ASUSTeK Computer Inc.
dmi.board.version: 1.0
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK Computer Inc.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrU40Sd.202:bd06/16/2011:svnASUSTeKComputerInc.:pnU40Sd:pvr1.0:rvnASUSTeKComputerInc.:rnU40Sd:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
dmi.product.family: U
dmi.product.name: U40Sd
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK Computer Inc.
mtime.conffile..etc.systemd.resolved.conf: 2018-04-19T19:34:54.154657

[Dan Streetman (ddstreet)]

please reopen if this is still an issue