Why does hostname --fqdn only return the domain name?

Question

Relevant files (slightly anonymized):

heinzi@d2:~$ cat /etc/hostname
d2
heinzi@d2:~$ cat /etc/hosts
127.0.0.1       localhost
<myexternalip>  d2.<myname>.at    <myname>.<myprovider>.at       <myname>

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

This output is correct:

heinzi@d2:~$ hostname
d2
heinzi@d2:~$ hostname --all-fqdns
d2.<myname>.at

But this I don't understand:

heinzi@d2:~$ hostname --fqdn
<myprovider>.at

Shouldn't it be d2.<myname>.at, since that's the first entry after <myexternalip>? And if it's the second entry, shouldn't it by <myname>.<myprovider>.at instead of just the domain name?

I'm aware that I could probably fix this by playing around with the hosts file, but I'd really like to understand why this happens. I read the hostname man page and googled and think that it should return d2.<myname>.at in my case. Thus, I'd really prefer an answer along the lines of "This is because ..." instead of "Try ... and see if it works.".

The system is Debian 7.5 "wheezy".

Answer 1

As it turns out, the culprit was /etc/resolv.conf. Changing:

search <myprovider>.at
nameserver ...
nameserver ...
nameserver ...

to

search <myname>.at <myprovider>.at
nameserver ...
nameserver ...
nameserver ...

fixes the issue.

(I'll leave the question open for the time being, just in case someone can come up with an explanation for this.)