dnsdomainname and hostname -f does not return FQDN

Question

I have one box (Rasberry Pi, running rasberian) with a static IP. It's running in a network with a domainname, and I have several DNS-server set up.

However, I can not get FQDN name to work on this box:

sitron@pi:~ $ domainname
(none)
sitron@pi:~ $ dnsdomainname 
sitron@pi:~ $ hostname -f
pi

I believe I have set up DNS correctly:

sitron@pi:~ $ hostname -I
192.168.10.9 2001:db8:abba::9 

sitron@pi:~ $ cat /etc/resolv.conf 
domain example.org
search example.org
nameserver 2001:db8:abba::5
nameserver 192.168.10.5

sitron@pi:~ $ dig +short -x 192.168.10.9 @2001:db8:abba::5
pi.example.org.

sitron@pi:~ $ dig +short -x 2001:db8:abba::9 @2001:db8:abba::5
pi.example.org.

sitron@pi:~ $ dig +short -x 2001:db8:abba::9 @192.168.10.5
pi.example.org.

sitron@pi:~ $ dig +short -x 192.168.10.9 @192.168.10.5
pi.example.org.

My nsswitch.conf:

# /etc/nsswitch.conf
#
# Example configuration of GNU Name Service Switch functionality.
# If you have the `glibc-doc-reference' and `info' packages installed, try:
# `info libc "Name Service Switch"' for information about this file.

passwd:         compat
group:          compat
shadow:         compat
gshadow:        files

hosts:          files mdns4_minimal dns
networks:       files

protocols:      db files
services:       db files
ethers:         db files
rpc:            db files

netgroup:       nis

And /etc/hosts:

127.0.0.1   localhost
::1     localhost ip6-localhost ip6-loopback
ff02::1     ip6-allnodes
ff02::2     ip6-allrouters

127.0.1.1   pi

What is the missing link?

Answer 1

I figured it out, and there is two solutions. I have tested both, on several different boxes.

Solution A

Verify that your resolv.conf contains the "domain"-keyword, like this:

# Generated by resolvconf
domain example.org
nameserver 127.0.0.1

If you are using dhcpcd.conf to set a static IP like me, you have to specify this undocumented option:

static domain_name=example.org

Finally, you need to remove the line in /etc/hosts containing 127.0.1.1 <hostname>. That means my /etc/hosts now contains:

127.0.0.1   localhost
::1     localhost ip6-localhost ip6-loopback
ff02::1     ip6-allnodes
ff02::2     ip6-allrouters

Solution B

Add your FQDN to the 127.0.1.1 line in /etc/hosts, like this:

127.0.0.1   localhost
::1     localhost ip6-localhost ip6-loopback
ff02::1     ip6-allnodes
ff02::2     ip6-allrouters

127.0.1.1   pi.example.org pi

However, this means I am overriding the DNS-server, something that is not ideal. That's why I prefer, and assume Solution A is better.