在ubuntu上安装完apache2,php5报错apr_sockaddr_..

故障现象：

root@UBUNTU:~# service apache2 restart
 * Restarting web server apache2                                                                              apache2: apr_sockaddr_info_get() failed for UBUNTU
apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName
 ... waiting apache2: apr_sockaddr_info_get() failed for UBUNTU
apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName