[Bug 1880258] Re: Add trailing dot to make connectivity-check.ubuntu.com. absolute and reduce NXDOMAIN warning noise

[Launchpad Bug Tracker]

This bug was fixed in the package systemd - 246.6-1ubuntu1.2

---------------
systemd (246.6-1ubuntu1.2) groovy; urgency=medium

  [ Ioanna Alifieraki ]
  * d/p/lp1911187-systemctl-do-not-shutdown-immediately-on-scheduled-shutdo.patch:
    Do not shutdown immediately when scheduled shutdown fails (LP: #1911187)
    https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=bbca658178d27e0ffaf759ba3115878d26c917a6

  [ Dan Streetman ]
  * d/p/debian/patches/lp1880258-log-nxdomain-as-debug.patch:
    Change NXDOMAIN 'errors' to log level debug (LP: #1880258)
    https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=b8e864eb907469616d688eab39b20491693d7c3a
  * d/p/lp1913763-udev-rules-add-rule-to-create-dev-ptp_hyperv.patch:
    Create symlink for hyperv-provided ptp device (LP: #1913763)
    https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=83c7476c80e4139ee7c1ec18a549c30d37d3b4b2

 -- Ioanna Alifieraki <ioanna-maria.alifieraki at canonical.com>  Tue, 23
Feb 2021 02:31:55 +0200

** Changed in: systemd (Ubuntu Groovy)
       Status: Fix Committed => Fix Released

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, 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 Released
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 Released
Status in network-manager source package in Hirsute:
  Fix Released
Status in systemd source package in Hirsute:
  Fix Released

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