1.備用源
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
2.換源
cd /etc/yum.repos.d
wget http://mirrors.aliyun.com/repo/Centos-7.repo
wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
3.清除及生成緩存
yum clean all
yum makecache
結束。