if PXE (or whatever network boot option your machine is running) fails to detect a network OS and there are any available options after it in the boot order, it'll boot into them.
If it's the last item and nothing else boots, it'll hang indefinitely at a screen that says something similar to "waiting for network operating system," in my admittedly limited experience, anyhow.
It depends on the boot order.
if PXE (or whatever network boot option your machine is running) fails to detect a network OS and there are any available options after it in the boot order, it'll boot into them.
If it's the last item and nothing else boots, it'll hang indefinitely at a screen that says something similar to "waiting for network operating system," in my admittedly limited experience, anyhow.