The Paravirtualized network adapter (virtio-net) is special. If you select this adapter, then Oracle VM VirtualBox does not virtualize common networking hardware that is supported by common guest operating systems. Instead, Oracle VM VirtualBox expects a special software interface for virtualized environments to be provided by the guest, thus avoiding the complexity of emulating networking hardware and improving network performance. Oracle VM VirtualBox provides support for the industry-standard virtio networking drivers, which are part of the open source KVM project.