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.

I'll make this guide quick and straight to the point. Follow these steps and Munin will be up and collecting stats quickly.

Prerequisites:
Apache and MySQL

Assumptions:
You are monitoring the same server that munin is installed on, The server's name is server1.example.com., /var/www = document root