A solution to the default invalid host only mode of CentOS virtual machine in VirtualBox

Because the network card is not activated at boot time.
Go to /etc/sysconfig/network-scripts/
Inside is the network card configuration file. Usually the hostonly configuration file name is: IFCFG-ENP0S8
If you open this file, you can see the ONBOOT=no line configuration. Change it to ONBOOT=yes and restart the virtual machine.

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