yum更新出错 yum update Error: Cannot find a valid baseurl for repo: addons

yum update Error: Cannot find a valid baseurl for repo: addons

yum update 

Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=5&arch=i386&repo=addons error was
[Errno 4] IOError: <urlopen error (-3, ‘Temporary failure in name resolution’)>
Error: Cannot find a valid baseurl for repo: addons

ping mirrorlist.centos.org 发现ping不通

ping www.baidu.com 发现也ping不通

但是该服务器是能连接外网的，怀疑是dns设置问题

需要修改/etc/resolv.conf文件

也可以用echo命令：

echo "nameserver 8.8.8.8" >> /etc/resolv.conf