CentOS 7虚拟机用着突然就ping不通了，问题是

[root@slave2 桌面]# <span style="color:#ff0000;">systemctl status network.service 
</span>network.service - LSB: Bring up/down networking
   Loaded: loaded (/etc/rc.d/init.d/network)
   Active: failed (Result: exit-code) since 三 2015-06-24 10:16:01 CST; 14s ago
  Process: 4861 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=1/FAILURE)

6月 24 10:16:01 slave2 network[4861]: RTNETLINK answers: File exists
6月 24 10:16:01 slave2 network[4861]: RTNETLINK answers: File exists
6月 24 10:16:01 slave2 network[4861]: RTNETLINK answers: File exists
6月 24 10:16:01 slave2 network[4861]: RTNETLINK answers: File exists
6月 24 10:16:01 slave2 network[4861]: RTNETLINK answers: File exists
6月 24 10:16:01 slave2 network[4861]: RTNETLINK answers: File exists
6月 24 10:16:01 slave2 network[4861]: RTNETLINK answers: File exists
6月 24 10:16:01 slave2 systemd[1]: network.service: control process exited...=1
6月 24 10:16:01 slave2 systemd[1]: <span style="color:#ff0000;">Failed to start LSB: Bring up/down netw...g.
</span>6月 24 10:16:01 slave2 systemd[1]: Unit network.service entered failed state.
Hint: Some lines were ellipsized, use -l to show in full.

一种解决方法是：systemctl stop NetworkManager.service

然后重启网络：  systemctl restart network.service

这两个都是管理网络的，关闭上面的