When starting Apache for the first time or after a networking change you get the following error:

httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName

This message is more of a warning than an error. If you check your running processes you will see the httpd process running. Basically Apache is telling you that it doesn't know the host name of your server. This is a simple fix.

Note that the instructions below are for CentOS/Redhat. They may be similar for your distro. You will need to know your IP address and the host name for your server. I will use Server1.example.com as the host name and 192.168.20.100 as the IP address.

1. Edit /etc/hosts using your favorite editor The contents should look something like this: # Do not remove the following line, or various programs # that require network functionality will fail. 127.0.0.1 localhost.localdomain localhost ::1 localhost6.localdomain6 localhost6
2. At the end of the file add: 192.168.20.100 Server1.example.com That's a [tab] between the IP address and the host name
3. Save the file
4. Restart the network services to apply your changes service network restart
5. Restart Apache service httpd restart