First, sorry for my English. In Debian documentation: https://www.debian.org/doc/manuals/debian-reference/ch03.en.html in chapter "3.2.5. The hostname", the author makes it clear that we should not use the FQDN in the file /etc/hostname: "This file should contain only the system hostname, not a fully qualified domain name." Why in the tutorial http://www.howtoforge.com/perfect-server-debian-wheezy-apache2-bind-dovecot-ispconfig-3-p3, Falko says it's important to be FQDN? Extracted from the original text: Now run Code: echo server1.example.com > /etc/hostname /etc/init.d/hostname.sh start Afterwards, run Code: hostname hostname -f "It is important that both show server1.example.com now!" Someone could help me with this issue? Tks!