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

Summary:
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apache 2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName

Step 1:
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We need to configure localhost as a server name in apache2 httpd file

$ sudo subl /etc/apache2/httpd.conf

Step 2:
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Add the following command and save the file

$ ServerName localhost


Step 3:
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Restart the apache2 server

$ sudo service apache2 restart