1, open the centos yum folder
cd /etc/yum.repos.d/
2, download repo file with wget
wget http://mirrors.aliyun.com/repo/Centos-7.repo
Here is the Ali Baba, you can also use source NetEase or other companies, to find their own URLs
If wget command does not take effect, indicating that no installation tool wget, enter yum -y install wget
Enter the installation.
The current directory is /etc/yum.repos.d/, just downloaded Centos-7.repo also on this directory
3, the original repo file backup system
mv CentOs-Base.repo CentOs-Base.repo.bak
4, the principle of replacing repo file system
mv Centos-7.repo CentOs-Base.repo
5, to perform the command yum update source
yum clean all
yum makecache
yum update
In order to perform the above three commands that is configured.