CentOS7下报错:Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock32 error was 14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"

Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock32 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 distribution release still work).
 
 3. Disable the repository, 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>
 
 4. 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

造成这种报错的原因是没有联网。

解决办法是

　　在终端中输入以下命令，查看安装在本机的网卡：nmcli d

　　cd /etc/sysconfig/network-scripts/本机网卡

　　　　  BOOTPROTO=dhcp
 　　　　 ONBOOT=yes

　　 然后，通过键入以下命令重新启动网络服务：

　　　　service network restart

　　ping一下百度试试。。。