Debian and FQDN lookup

[Mihamina Rakotomandimby]

Hi al,

WHen issuing 'hostname --fqdn', I'm supposed to get the FQDN.
Anyway when trying some different combinations, involving /etc/hostname, 
/etc/domainname, /etc/hosts, /etc/resolv.conf, I cannot figure out where 
the FQDN is looked up AND with what precedence.
Would you know the mechanism (precedence) and worlkflow where a Debian 7 
machine gets its FQDN?

Thank you.