执行yum install xxx出现 Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was 14: curl#6 - "Could not resolve host: mirrorlist.centos.org; 未知的错误"

解决办法：

1、备份镜像源/etc/yum.repos.d/CentOS-Base.repo文件

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

2、下载aliyun的yum镜像源

curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

3、更新缓存

yum clean all

yum makecache

4、再执行对应的 install | update 等命令