CentOS7 执行yum 命令报错 One of the configured repositories failed (Unknown)

最近在本机虚拟机上最小化安装了centos7，安装完毕后执行yum命令报错，

One of the configured repositories failed (Unknown),  
 and yum doesn't have enough cached data to continue. At this point the only  
 safe thing yum can do is fail. There are a few ways to work "fix" this:  
  
     1. Contact the upstream for the repository and get them to fix the problem.  
  
     2. Reconfigure the baseurl/etc. for the repository, to point to a working  
        upstream. This is most often useful if you are using a newer  
        distribution release than is supported by the repository (and the  
        packages for the previous distribution release still work).  
  
     3. Disable the repository, so yum won't use it by default. Yum will then  
        just ignore the repository until you permanently enable it again or use  
        --enablerepo for temporary usage:  
  
            yum-config-manager --disable   
  
     4. Configure the failing repository to be skipped, if it is unavailable.  
        Note that yum will try to contact the repo. when it runs most commands,  
        so will have to try and fail each time (and thus. yum will be be much  
        slower). If it is a very temporary problem though, this is often a nice  
        compromise:  
  
            yum-config-manager --save --setopt=.skip_if_unavailable=true  
  
Cannot find a valid baseurl for repo: base/7/x86_64

解决方式如下：

1.检查网络配置情况

  首先ping一下114.114.114.114，看是否能ping通。若通，则跳过此步骤。不通，则可参考下方链接：

   https://www.cnblogs.com/owaowa/p/6123902.html

2.更新base.repo源

 网络问题解决后，再试试yum命令能否成功，要是仍旧报错：

1.备份文件

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

2、下载新的CentOS-Base.repo 到/etc/yum.repos.d/

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

或者

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

3、运行yum makecache生成缓存

  参考：

https://www.cnblogs.com/owaowa/p/6123902.html

https://opsx.alibaba.com/mirror