Sometimes when we start or restart Apache2 The following error appears in the terminal:
Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName
The correct domain name for the server could not be determined, 127.0.0.1 will be used as ServerName
To solve it we simply must execute the following command:
echo "ServerName localhost" >> /etc/apache2/conf.d/fqdn
This will be enough to solve the problem, from now on when they start or restart Apache2 they will no longer show that error.