[root@cloud test]# yum list
已加载插件：fastestmirror
: [Errno 14] curl#6 - "Could not resolve host: mirrors.163.com; 未知的错误"
正在尝试其它镜像。
One of the configured repositories failed (CentOS-7 - Base - 163.com),
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. Run the command with the repository temporarily disabled
yum --disablerepo=base ...
4. Disable the repository permanently, 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 base
or
subscription-manager repos --disable=base
5. 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=base.skip_if_unavailable=true
failure: repodata/repomd.xml from base: [Errno 256] No more mirrors to try.
如果使用 yum list 或者安装某文件时提示这种报错，host 解析有问题，请检查网络 DNS 设置，重启网络服务，OK。
更多YUM相关教程见以下内容：
CentOS及Red Hat Linux安装yum源
RedHat7.0配置本地yum源