httpd: Could not reliably determine the server's fully qualified domain name

解决方案:
进入apache的安装目录:

Windows : D:/Program Files/Apache Software Foundation/Apache2.2conf
linux : /usr/local/apache/conf

用记事本打开httpd.conf
将里面的:

#ServerName localhost:80

注释去掉即可.
再执行:

service httpd start

然后可以通过浏览器访问http://localhost:80,如果页面显示"It works!",即表示apache已安装并启动成功.