Failed to start LSB: Bring up/down networking 虚拟机不能上网

最近在CentOS7中经常碰到虚拟机连不上网的问题，错误代码如下。

Restarting network (via systemctl):  Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details.

[失败]

使用systemctl status network.service命令查看结果如下：

network.service - LSB: Bring up/down networking

Loaded: loaded (/etc/rc.d/init.d/network)

Active: failed (Result: exit-code) since 三 2016-08-17 11:34:36 CST; 54s ago

Docs: man:systemd-sysv-generator(8)

Process: 3847 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=1/FAILURE)

8月 17 11:34:36 python.cn network[3847]: RTNETLINK answers: File exists

8月 17 11:34:36 python.cn network[3847]: RTNETLINK answers: File exists

8月 17 11:34:36 python.cn network[3847]: RTNETLINK answers: File exists

8月 17 11:34:36 python.cn network[3847]: RTNETLINK answers: File exists

8月 17 11:34:36 python.cn network[3847]: RTNETLINK answers: File exists

8月 17 11:34:36 python.cn network[3847]: RTNETLINK answers: File exists

8月 17 11:34:36 python.cn systemd[1]: network.service: control process exited, code=exited status=1

8月 17 11:34:36 python.cn systemd[1]: Failed to start LSB: Bring up/down networking.

8月 17 11:34:36 python.cn systemd[1]: Unit network.service entered failed state.

8月 17 11:34:36 python.cn systemd[1]: network.service failed.

网络上的办法行不通，如： CentOS7 Failed to start LSB: Bring up/down解决方法也行不通。

最后解决的办法就是将dhcp服务器重启一下，步骤如图所示：

• 保证虚拟机在关机的状态下；
• 点击编辑按钮选择虚拟网络编辑器；
• 点击更改设置按钮；
• 点击还原默认设置。