The difference between three modes:
Bridge mode: ip to a virtual machine, as long as the host can access the Internet, a virtual machine can be accessed via host mapping, two machines can communicate with each other.
NAT mode: the host and the virtual machine at the same address, can communicate with each other both in principle, but modify the NAT configuration, communicate with each other through port forwarding.
Only the host mode: the more fierce, by default, can not access the Internet, you need to configure routes or agent
Only a plurality of virtual machine host mode can communicate with each other in the same segment, configure different segments ip address.