yum 提示找不到镜像的问题：Couldn't resolve host 'mirrorlist.centos.org'

问题：
[root@cddserver2 ~]# yum -y install gcc-*
Loaded plugins: fastestmirror, presto
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=6&arch=x86_64&repo=os error was
14: PYCURL ERROR 6 - "Couldn't resolve host 'mirrorlist.centos.org'"
Error: Cannot retrieve repository metadata (repomd.xml) for repository: base. Please verify its path and try again

原因：
 dns服务器没有配置正确

解决办法：
1、打开文件/etc/resolv.conf在其中添加：
 nameserver 8.8.8.8
 #nameserver 8.8.4.4
 #search localdomain

2、然后重启网卡：使用命令: service network restart