Network in Ubuntu 18.04 on VirtualBox

Network in Ubuntu 18.04 on VirtualBox
Go to directory /etc/netplan
There is one example file named  50-cloud-init.yaml
> cat /etc/netplan/50-cloud-init.yaml
network:
    ethernets:
        enp0s3:
            addresses: []
            dhcp4: true
        enp0s8:
            dhcp4: no
            addresses: [192.168.56.103/24]
            gateway4: 192.168.56.0
            nameservers:
                    addresses: [8.8.8.8,8.8.4.4]
    version: 2
Enable the network
> sudo netplan apply
Then the network is cool now.
ifconfig
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.0.2.15  netmask 255.255.255.0  broadcast 10.0.2.255
        inet6 fe80::a00:27ff:fe28:fedb  prefixlen 64  scopeid 0x20<link>
        ether 08:00:27:28:fe:db  txqueuelen 1000  (Ethernet)
        RX packets 2  bytes 1180 (1.1 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 14  bytes 1618 (1.6 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
enp0s8: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.56.103  netmask 255.255.255.0  broadcast 192.168.56.255
        inet6 fe80::a00:27ff:fea0:f650  prefixlen 64  scopeid 0x20<link>
        ether 08:00:27:a0:f6:50  txqueuelen 1000  (Ethernet)
        RX packets 269  bytes 22943 (22.9 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 615  bytes 58115 (58.1 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 234  bytes 15624 (15.6 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 234  bytes 15624 (15.6 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

References:
https://linuxconfig.org/how-to-configure-static-ip-address-on-ubuntu-18-04-bionic-beaver-linux