Could Not Reliably Determine The Server Fully Qualified Domain Name

Problem

When starting Apache2, you are met with the following notice:

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

Solution

Set the ServerName variable.

# Example of setting the Apache2 ServerName variable to 'localhost'
echo "ServerName localhost" | sudo tee /etc/apache2/conf.d/fqdn

# Restarting the service should no longer present the notice.
service apache2 restart

References

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