with -release version of systemd: root@lp1880258-g:~# host afhjisrfljsdirfj.com Host afhjisrfljsdirfj.com not found: 3(NXDOMAIN)
root@lp1880258-g:~# journalctl -b -u systemd-resolved --no-pager ... Mar 09 18:07:46 lp1880258-g systemd-resolved[624]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature level UDP. Mar 09 18:09:11 lp1880258-g systemd-resolved[624]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature level UDP. Mar 09 18:09:14 lp1880258-g systemd-resolved[624]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature level UDP. root@lp1880258-g:~# dpkg -l systemd|grep systemd ii systemd 246.6-1ubuntu1.2 amd64 system and service manager root@lp1880258-g:~# host afhjisrfljsdirfj.com Host afhjisrfljsdirfj.com not found: 3(NXDOMAIN) root@lp1880258-g:~# host afhjisrfljsdirfj.com Host afhjisrfljsdirfj.com not found: 3(NXDOMAIN) root@lp1880258-g:~# host afhjisrfljsdirfj.com Host afhjisrfljsdirfj.com not found: 3(NXDOMAIN) root@lp1880258-g:~# journalctl -b -u systemd-resolved --no-pager | grep NXDOMAIN root@lp1880258-g:~# ** Tags removed: verification-needed-groovy ** Tags added: verification-done-groovy -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1880258 Title: Add trailing dot to make connectivity-check.ubuntu.com. absolute and reduce NXDOMAIN warning noise Status in network-manager package in Ubuntu: Fix Released Status in systemd package in Ubuntu: Fix Committed Status in systemd source package in Bionic: Fix Committed Status in systemd source package in Focal: Fix Committed Status in systemd source package in Groovy: Fix Committed Status in network-manager source package in Hirsute: Fix Released Status in systemd source package in Hirsute: Fix Committed Bug description: [impact] systemd-resolved emits a disturbingly large amount of NXDOMAIN log messages that do not actually indicate any real problem [test case] see original description, or look at any log from any recent Ubuntu system, or search google for endless complaints about NXDOMAIN messages logged by Ubuntu [regression potential] any regression would likely be isolated to systemd-resolved handling of a NXDOMAIN response from its upstream nameserver, including possibly failing to resolve a hostname or delays in resolving hostnames [scope] this is needed for all releases; the patch is not upstream, but carried by Ubuntu [original description] I normally don't like this, but it's a one-character change so it's easier to start with the solution: diff -u -r1.1 /usr/lib/NetworkManager/conf.d/20-connectivity-ubuntu.conf --- /usr/lib/NetworkManager/conf.d/20-connectivity-ubuntu.conf +++ /usr/lib/NetworkManager/conf.d/20-connectivity-ubuntu.conf @@ -1,2 +1,2 @@ [connectivity] -uri=http://connectivity-check.ubuntu.com/ +uri=http://connectivity-check.ubuntu.com./ Making this name absolute instead of relative avoids spurious resolutions of "connectivity-check.ubuntu.com.your_domain." This removes a fair amount of NXDOMAIN error noise in journalctl. Observing the issue and the fix requires 3 terminals: 1. tcpdump -i any 'port domain' 2. journalctl --boot -u systemd-resolved -f 3. nmcli c down "Wired connection 1"; nmcli c up "Wired connection 1" => observe the NXDOMAIN noise over a couple few minutes Now make the hostname absolute with the trailing dot above and run: systemctl reload NetworkManager Wait 1 min for things to stabilize. Test again: nmcli c down "Wired connection 1"; nmcli c up "Wired connection 1" => observe non-zero but significantly reduced NXDOMAIN noise over a couple few minutes Originally reported at https://askubuntu.com/a/1242611/117217 Plenty of people annoyed by NXDOMAIN warnings, just Google it. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1880258/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
