修改CentOS默认yum源为mirrors.163.com
1、首先备份系统自带yum源配置文件/etc/yum.repos.d/CentOS-Base.repo
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
2、进入yum源配置文件所在的文件夹
cd /etc/yum.repos.d/
3、下载163的yum源配置文件到上面那个文件夹内
CentOS7:wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
CentOS6:wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
CentOS5:wget http://mirrors.163.com/.help/CentOS5-Base-163.repo
4、运行yum makecache生成缓存
yum makecache
5、这时候再更新系统就会看到以下mirrors.163.com信息
来源：https://www.cnblogs.com/raorao1994/p/9296772.html