Centos7 yum命令异常报错：Could not retrieve mirrorlist http://mirrorlist.centos.org

一、问题背景

vmware安装CentOS-7-x86_64-DVD-2009版本后，执行yum -y install gcc报错Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was

[root@centos ]# yum -y install gcc
已加载插件：fastestmirror, langpacks
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:

     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

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

二、问题解决

1、检查ip地址是否正常

执行命令ip addr 查看ip地址是否正常显示

以上图中没有显示出ip地址，说明网络有问题。接着操作下面的步骤

2、检查网络配置是否正常

在linux下ping www.baidu.com一下看看是不是网络链接正常。出现这种原因就是一般网络没链接好。那修改一下dns，找到/etc/sysconfig/network-scripts/ifcfg-ens33
注意一下，ifcfg-ens33后面的数字是随机产生的

将onboot改为yes，重新启动网络，service network restart，然后ping www.baidu.com如果通了的话，就证明链接成功。这样就可以正常yum -y install gcc了