替换为阿里云的镜像源：
[root@zn ~]# rm -rf /etc/yum.repos.d/*[root@xiaochen ~]# wget http://mirrors.aliyun.com/repo/Centos-6.repo -O /etc/yum.repos.d/CentOS-Base.repo
[root@zn ~]# wget http://mirrors.aliyun.com/repo/Centos-6.repo -P /etc/yum.repos.d
[root@zn ~]# yum clean all[root@xiaochen ~]# yum makecache
替换为网易163的镜像源：
[root@zn ~]# curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.163.com/.help/CentOS7-Base-163.repo
[root@zn ~]# yum clean all
[root@zn ~]# yum makecache
