Different types of virtual networks
VirtualBox supports several types for virtual networks. NAT is the simplest option from the point of view of the guest system for accessing external networks. Your host will act as a router and your hosts will be on a private subnet. Use this if you’re not running servers on the guests. However, the VMs can’t access each other, and neither can you access them from the host.
If you want the guests to access each other, then use the NAT Network mode. This groups the VMs that use it into a network, which can’t be accessed from outside the network. However, any VMs using this NAT network will be able to communicate with each other and also access the Internet.
The easiest option for accessing the VMs from the host and other machines on the network is bridged networking mode. Your guests will receive an IP address on the same subnet as your host. This type of network mode is useful if you’re running servers on the guest and wish to connect to it from other computers on the LAN.
Then there’s Internal Network that we’ve used in the tutorial. In this mode only those guests that have been connected to the same internal network will be able to communicate with each other in the internal network configuration. Communication with the host system or another network outside of VirtualBox isn’t possible. If you want to include the host in the internal network as well, use the Host Network mode that enables the guests to communicate with the host as well.