解决Centos使用yum命令报错“Cannot find a valid baseurl for repo: base/7/x86_64”问题

一、问题描述

        我们在使用Centos7.9使用【sudo yum install influxdb2】命令安装influxDB数据库的时候提示“Loading mirror speeds from cached hostfile 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:

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