Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=6&arch=x86_64&repo=os error was

[root@localhost ~]# yum update
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
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 find a valid baseurl for repo: base

Last login: Thu Jul 14 22:01:02 2016 from 192.168.1.105
[root@haishengtech ~]# more /etc/resolv.conf
nameserver 8.8.8.8 
[root@haishengtech ~]#