nsswitch.conf configuration doesn't work with mdns hosts

[Alberto Donato]

On a fresh Ubuntu 16.10 (yakkety) install, resolution of mDNS hosts doesn't work anymore (it used to in xenial)

I can resolve names with avahi-resolve but ssh,ping,etc. fail to resolve.

After some digging I found out that what's causing it is the "resolve" option in /etc/nsswitch.conf:

hosts: files resolve [!UNAVAIL=return] mdns4_minimal [NOTFOUND=return] dns

Changing it to

hosts: files mdns4_minimal [NOTFOUND=return] dns

(as it was on xenial) makes mDNS work again.

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: libnss-resolve 231-9ubuntu2
ProcVersionSignature: Ubuntu 4.8.0-30.32-generic 4.8.6
Uname: Linux 4.8.0-30-generic x86_64
ApportVersion: 2.20.3-0ubuntu8
Architecture: amd64
Date: Fri Dec 16 15:16:38 2016
InstallationDate: Installed on 2016-10-22 (54 days ago)
InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2)
SourcePackage: systemd
UpgradeStatus: No upgrade log present (probably fresh install)

[Paul White (paulw2u)]

Thanks, edit of nsswitch.conf worked for me. Also marking as affecting zesty.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Sebastian Malcolm (smalcolm)]

Use the re-ordering of hosts line in nsswitch.conf posted by Mark Tearle in #1641328:
   files mdns4_minimal [NOTFOUND=return] resolve [!UNAVAIL=return] dns

This is better than removing "resolve [!UNAVAIL=return]" because recent Ubuntu releases should continue to use systemd-resolved for name resolution. It's man page explains several benefits, see:
 https://www.freedesktop.org/software/systemd/man/systemd-resolved.service.html