VM Ubuntu Ping Unknow host how to Troubleshoot

For example, the gateway address is: 192.168.1.1

Route add default GW 192.168.1.1  
sudo vim/etc/resolv.conf

Join in the/etc/resolv.conf

# generated by NetworkManager  
nameserver 192.168.1.1

After the modification can be normal ping, but the system reboot after the ping will show the Unknow host, so you need to lock the/etc/resolv.conf file, do not allow the system to start rewriting.

sudo chattr +i/etc/resolv.conf

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