Centos7中Could not resolve host: mirrorlist.centos.org; 未知的错误"

报错内容：

 

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=<repoid> ...

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 <repoid>
or
subscription-manager repos --disable=<repoid>

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=<repoid>.skip_if_unavailable=true

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

 1、先检查网络

ping www.baid.com

 

连接百度

 2、如果可以联网，则更换阿里云镜像源，直接下载就行

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

 

vi /etc/yum.repos.d/CentOS-Base.repo

 

更换CentOS-Base.repo文件

3、最后依次输入

yum clean all
rm -rf  /var/cache/yum/
yum makecache