>Heh, we were doing this 20-25 years ago.
It's possible, but I'd be surprised (unless you mean X servers in the crazy X-windows server-is-really-what-any-sane-person-would-call-a-client sense).
Doing this kind of thing is pretty new for servers. Even massive HPC clusters tend to boot from persistent disk.
I mean, it didn't go as smoothly as pxe booting does today; we ended up needing to reflash all our network cards to make it work, something I have not had to do in the last 5 years.
Well, they used bootp followed by tftp, and so did most other UNIX workstations of that time period. DHCP is effectively a superset of bootp -- it uses the same UDP port. PXE is DHCP+tftp along with some specification of tftp paths, where the image is loaded in RAM, etc.
Really the overall netboot mechanism is nearly identical as it was 25 years ago, just some protocol tweaks and a new acronym.
Not really, no. Servers all over the IT world have been using PXE and tftpboot for decades - in fact it was a very common method of booting a server even in the 80's. I know of quite a few Rail/Transportation companies whose track-side computers are booted over the network using these techniques, and there are about 250,000 of those things just in Europe alone ..
What's new is that another generation are discovering this technique.