Loaded plugins: fastestmirror, langpacks

Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was

12: Timeout on http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock: (28, ‘Resolving timed out after 31656 milliseconds‘)

 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 <repoid>

     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=<repoid>.skip_if_unavailable=true

Cannot find a valid baseurl for repo: base/7/x86_64

找了好久的问题，发现时域名解析器DNS的问题，这边只需要设置下面的DNS地址，当重启网络的时候会在/etc/resolv.conf文件下生成对应的域名

1、执行命令：vi /etc/sysconfig/network-scripts/ifcfg-ens33             进入网络配置

 2、需要把ONBOOT属性改成yes，并且加一个DNS1=114.114.114.114

然后执行命令：wq

 3、再执行命令systemctl restart network

再次访问 yum install ifconfig     成功解决

Centos7 yum命令异常报错Could not retrieve mirrorlist http://mirrorlist.centos.org