【CentOS7.6】yum 报错：Could not retrieve mirrorlist http://mirrorlist.centos.org

今天安装了一个虚拟机，准备用yum命令安装jdk的时候，出现了以下报错。

[root@node1 yum.repos.d]# yum install ifconfig
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
Could not retrieve mirrorlist http://mirrorlist.centos.org?arch=x86_64&release=7&repo=sclo-sclo error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"


 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 distri