I’m one of those guys who is always struggling with the network configuration of VirtualBox images. I understand NAT, but what is the effect? And what the heck is the difference between Bridged Networking and Internal Networking?
On the Oracle site are also found blogs. A great one is from the Fat Bloke and contains a post which explains the configuration of Virtualbox networking all very simple:
https://blogs.oracle.com/fatbloke/entry/networking_in_virtualbox1
If you have any problems with connectivity between your guest and host, go check out this article! It also explains very clearly when to use what configuration.