centos使用yum报错＂Could not resolve host: mirrorlist.centos.org; 未知的错误＂ centos使用yum报错

centos使用yum -y install报错"Could not resolve host: mirrorlist.centos.org; 未知的错误"

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"

One of the configured repositories failed (未知),
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= ...
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
or
subscription-manager repos --disable=
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=.skip_if_unavailable=true

googel了一下这个错误，发现报错原因是“本机无法连接网络的网络设置”的原因。
于是参照“How to Setup network on centos 7”这篇博文，配置了下DHPC，最终解决了这个error。
配置CentOS 7的网络，步骤如下：
1.在终端中输入以下命令，查看安装在本机的网卡：