I'm running the NetBoot service on a box running Mac OS X 10.5.6 server. I've been changing images to serve up, and most of them work, but the last one I tried doesn't -- if you go to System Preferences -> Startup Disk on a client, it doesn't see a specific network startup option.
It occurs to me to ask how the server advertises its services. I know it uses the Boot Service Discover Protocol (BSDP) which (as I understand it) can also act as a DHCP server. It would seem then that running:
ipconfig getpacket en0
possibly as root, would show something related to NetBooting, but it doesn't appear to.
Likewise, I know that a NetBoot server does not have to be your DHCP server. Therefore one would think it uses mDNS to advertise itself. When I fire up Bonjour Browser, though, I don't identify anything that says to me, "Ah, there is my NetBoot service."