mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
CentOS 7
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
3、之后运行yum makecache生成缓存
http://mirrors.aliyun.com/help/centos
原文：http://www.cnblogs.com/SciProgrammer/p/7795346.html