Could not reliably determine the server’s fully qualified domain name Ubuntu?

If you get next error:

Restarting web server apache2
apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName
... waiting apache2:
Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName

Solution:
vi  /etc/apache2/conf.d/fqdn
or vi  /etc/apache2/conf-available/fqdn.conf  ( for Ubuntu 14.04 )
 add
ServerName server.domain.org
 a2enconf fqdn