I unplugged the network cable in the VM.The icon near the clock then showed me that the network is disconnected. Ping 220.127.116.11 showed me this clearly. But Ping by DNS name of any one node fulfills in a few seconds. It seems that the system tries to resolve the DNS name, even if the network is disconnected. In my opinion, this can significantly slow down some apps while disconnected from the network. For example, they may try for a long time to check for updates, what to do is not possible. P.S. I think that when the network is unavailable, it would be right to only view the hosts file.