如何使用静态IP地址设置主机和httpd.conf文件

I set Centos 6.3 up on a Rackspace box, using a static IP address (not a FQDN). I will be setting up virtual hosts on this box, and it seems to be working fine, but when I restart the HTTPD server, I get an error message "could not reliably determine the server's fully qualified domain name, using xx.xxx.xx.xx for ServerName" (xx.xxx.xx.xx is the static IP address for the server).I set Centos 6.3 up on a Rackspace box, using a