3、下载163的yum源配置文件到上面那个文件夹内

CentOS7

[root@localhostyum.repos.d]#wgethttp://mirrors.163.com/.help/CentOS7-Base-163.repo

CentOS6

#wgethttp://mirrors.163.com/.help/CentOS6-Base-163.repo

CentOS5

#wgethttp://mirrors.163.com/.help/CentOS5-Base-163.repo

4、运行yum makecache生成缓存

#yummakecache

5、这时候再更新系统就会看到以下mirrors.163.com信息

#yum-yupdate 已加载插件：fastestmirror,refresh-packagekit,security 设置更新进程Loadingmirrorspeedsfromcachedhostfile *base:mirrors.163.com *extras:mirrors.163.com *updates:mirrors.163.com

修改CentOS默认yum源为mirrors.aliyun.com
1、首先备份系统自带yum源配置文件/etc/yum.repos.d/CentOS-Base.repo

2、下载ailiyun的yum源配置文件到/etc/yum.repos.d/
CentOS7

#wget-O/etc/yum.repos.d/CentOS-Base.repohttp://mirrors.aliyun.com/repo/Centos-7.repo

#wget-O/etc/yum.repos.d/CentOS-Base.repohttp://mirrors.aliyun.com/repo/Centos-6.repo