virtualbox.org

Host-only is intended for the host and the guest to talk "only" It will not talk to another host or guest of that other host.
If this is not what you need then you should go a different direction, but I assure you that the solution I posted will fix the unknown network issue.
Perhaps you really want to use Bridged.

saberman wrote:The solution given is to set the gateway to another active host on the subnet. This is a Host-only Network with only one host. There isn't another active host on the subnet.

The host only network has two active machines on it - the host and the guest. Setting the default gateway of the guest to the IP of the host only adapter on the physical machine will solve the problem of unidentified networks in the guest OS.

If you are getting the unidentified network messages it the host, you will need to change the security policy in the host OS to allow unidentified networks to be private and allow file sharing.