If you are starting to use of virtual machine, you should familiar with some basic networking concept. In virtualization, there is four networking modes available in every hypervisor. NAT, Bridged networking, Internal networking, and Host only. These modes help you to manage your network setting in guest machine, within guest machines, between guest and host machine and between guest and public network or private network.
Network Address Translation (NAT) :
NAT configures your virtual machine to share the IP and MAC addresses of the host. The virtual machine and the host share a single network identity that is not visible outside the network. NAT can be useful when you are allowed a single IP address or MAC address by your network administrator. You might also use NAT to configure separate virtual machines for handling http and ftp requests, with both virtual machines running off the same IP address or domain. If all you want is to browse the Web, download files and view e-mail inside the guest, then this default mode should be sufficient for you, and you can safely skip the rest of this section.
If you use NAT, your
virtual machine does not have its own IP address on the external network.
Instead, a separate private network is set up on the host computer. Your
virtual machine gets an address on that network from the virtual DHCP server.
The NAT device passes network data between one or more virtual machines and the
external network. It identifies incoming data packets intended for each virtual
machine and sends them to the correct destination.
Bridged networking :
Bridged networking connects a virtual machine to a network using the host
computer's Ethernet adapter. This is for more advanced networking needs such as
network simulations and running servers in a guest. When enabled, Virtual Machine
connects to one of your installed network cards and exchanges network packets
directly, circumventing your host operating system’s network stack. If your
host computer is on an Ethernet network, this is often the easiest way to give
your virtual machine access to that network. Linux and Windows hosts can use
bridged networking to connect to both wired and wireless networks.
If you use bridged
networking, the virtual machine is a full participant in the physical network.
It has access to other machines on the network and can be contacted by other
machines on the network as if it were a physical computer on the network.
Internal networking :
This can be used to create a different kind of software-based network which
is visible to selected virtual machines, but not to applications running on the
host or to the outside world. if you are using internal networking you can make connectivity between your guest machines only not with your host machine and public or private network.
Host-only
networking :
This can be used to create
a network containing the host and a set of virtual machines, without the need
for the host’s physical network interface. Instead, a virtual network interface
(similar to a loopback interface) is created on the host, providing
connectivity among virtual machines and the host.
