PXE Network Boot VirtualBox
You need host networking enabled to boot via the network. Check here for prerequisite configuration.
VirtualBox is capable of network boot, and is practically indistinguishable in configuration as compared to a real machine. To PXE boot a VirtualBox guest OS open the settings of a guest OS:
Click the system tab:
To enable PXE boot you have to configure the following section:
Then use the up and down arrows to set the priority of the network boot feature, as shown above.
You can create a guest OS that has no hard drive; there is no need for one. In such a configuration make network boot the first on the list.
Since you intend to use PXE boot, you may consider setting up a LTSP server.