[Bug 1658592] Re: systemd-resolved causing google.com not reachable

[Dimitri John Ledkov]

You may also use dig, to discover and check things by-passing resolved.

E.g. $ dig google.com.sg @8.8.8.8

Note that 8.8.8.8 is globally distributed DNS using anycast routing,
meaning the results from 8.8.8.8 that I see, may not be the results you
see.

google.com.sg looks ok for me, and google.com too. However, the redirect
from google.com -> google.com.sg is location dependant.

If you hit, this or similar problem in the future, it would be helpful to attach output of $ systemd-resolve --status
As that shows what upstream DNS servers resolved is using. Most of the time, using 8.8.8.8 is the wrong answer, and you should, ideally, use your internal workplace and/or ISP DNS =)

Furthermore '$ journalctl -b -e -u systemd-resolved' may show warnings
and errors from DNS resolutions.

$ systemd-resolve --flush-caches
$ systemd-resolve --reset-server-features

Are also useful debugging tools, to flush resolved state - drop cached
responses, and revert to trying DNS requests with highest feature set
(e.g. with EDNS0 / dnssec / etc).

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https://bugs.launchpad.net/bugs/1658592

Title:
  systemd-resolved causing google.com not reachable

Status in systemd package in Ubuntu:
  Expired

Bug description:
  System info:
  lsb_release -rd: Description:	Ubuntu Zesty Zapus (development branch)
  Release:	17.04

  uname -a:
  Linux pc 4.9.0-12-generic #13-Ubuntu SMP Mon Jan 9 20:06:25 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

  systemd --version:
  systemd 232
  +PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN

  Static IP address(10.0.0.250/16), DNS(8.8.8.8) and routes(10.0.0.1)
  are set manually in network manager.

  Problem Description:

  1. google.com is not accessible from firefox or chromium, but
  google.co.uk, google.co.jp can be accessble. Firefox would redirect
  google.com to
  "https://www.google.com.sg/?gfe_rd=cr&ei=eaCFWLfUDIe1vASXoY7gBA"
  reports an error "Firefox can’t find the server at www.google.com.sg."
  Chromium redirect to google.com.sg too and reports a DNS error.

  2. ping and host google.com shows no errors and reports correct IP
  addresses.

  3. ping: google.com.sg: Name or service not known

  4. host google.com.sg: google.com.sg has address 74.125.130.94

  5. entering 74.125.130.94 directly in Firefox address bar redirect the
  webpage to
  "https://www.google.com.sg/?gfe_rd=cr&ei=paKFWO2sJ9LFuASvwq2ADA"

  6. other PC running fedora distro in the same lan can reach google.com
  with firefox or chromium.

  7. Looking at /etc/resolve.conf, nameserver is 127.0.0.53. It also
  suggests systemd-resolved.service is in charge of name resolution. If
  I stop this service and change nameserver in /etc/resolv.conf to
  8.8.8.8, `google.com` can be accessed from firefox.

  8. If changing nameserver back to 127.0.0.53 and start systemd-
  resolved.service, google.com is not accessible from browser anymore.

  The above step seems to suggest the problem is with systemd-
  resolved.service.

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