参考于：
http://mirrors.aliyun.com/help/centos?spm=5176.bbsr150321.0.0.d6ykiD
1、备份原文件
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo_bak
2、下载新的repo文件
CentOS 5
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo
CentOS 6
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
CentOS 7
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
网易源centos6
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.163.com/.help/CentOS6-Base-163.repo
[root@rac1 yum.repos.d]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.163.com/.help/CentOS6-Base-163.repo --2017-10-14 23:18:31-- http://mirrors.163.com/.help/CentOS6-Base-163.repo 正在解析主机 mirrors.163.com... 123.58.190.209,123.58.190.228,123.58.190.234,... 正在连接 mirrors.163.com|123.58.190.209|:80... 已连接。 已发出 HTTP 请求，正在等待回应... 200 OK 长度：2006 (2.0K) [application/octet-stream] 正在保存至: “/etc/yum.repos.d/CentOS-Base.repo” 100%[=========================================================>] 2,006 --.-K/s in 0.001s 2017-10-14 23:18:31 (1.90 MB/s) - 已保存 “/etc/yum.repos.d/CentOS-Base.repo” [2006/2006])
3、如果报域名解析失败：
[root@RAC01 yum.repos.d]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo --2017-10-14 01:22:16-- http://mirrors.aliyun.com/repo/Centos-6.repo 正在解析主机 mirrors.aliyun.com... 失败：域名解析暂时失败。 wget: 无法解析主机地址 “mirrors.aliyun.com”
4、新增dns域名地址
新增下面一条内容：
[root@RAC01 yum.repos.d]# vi /etc/resolv.conf
nameserver 8.8.8.8
5、生成缓存
[root@RAC01 yum.repos.d]# yum makecache Loaded plugins: fastestmirror,security Loading mirror speeds from cached hostfile * base: mirrors.aliyun.com * extras: mirrors.aliyun.com * updates: mirrors.aliyun.com base | 3.7 kB 00:00 base/group_gz | 226 kB 00:00 base/filelists_db | 6.4 MB 00:02 base/primary_db | 4.7 MB 00:01 base/other_db | 2.8 MB 00:00 extras | 3.4 kB 00:00 extras/filelists_db | 25 kB 00:00 extras/prestodelta | 1.3 kB 00:00 extras/primary_db | 29 kB 00:00 extras/other_db | 30 kB 00:00 updates | 3.4 kB 00:00 updates/filelists_db | 2.9 MB 00:00 updates/prestodelta | 130 kB 00:00 updates/primary_db | 4.7 MB 00:01 updates/other_db | 66 MB 00:18 Metadata Cache Created
6、ok。
