Configuring Apache on CentOS
Solution 1:
Try This:
Service iptables stop
service httpd restart
NOTE: the reason is that by default CentOS installation has the Firewall On, then what we did here is to disable it, but when you restart then activates again with this command: "chkconfig iptables off" we disable it permanently.
but you can also add a rule to allow port rute 80 if you want
Solution 2:
Check to make sure you have a valid hosts entry in /etc/hosts. Apache won't start successfully without it.