NetBooting occasionally fails

Question

Hello,
I'm not sure if this is the right section for this, but I don't see a NetBoot section and I guess this is the closest thing.
I've set my lab to NetBoot from an XServe using ARD's Set Startup Disk command. I rebooted everything and a few machines started from their internal disk. I labeled those machines red in ARD, manually netbooted them (holding down the N key) then I reset the startup disk on those clients and rebooted everything again. This time DIFFERENT clients tried to boot from their internal drives. I did the same thing and rebooted yet again. This time everything NetBooted, no need to hold down the N key on any machines. Did it again just to double check and everything came up again. Hooray!
A little while later I restarted the lab again for other reasons only to find that nearly half of the computers tried to boot from their internal drives. This time I simply restarted the naughty computers, not bothering to hold down "N." Each and every one of them netbooted. So Startup Disk isn't getting unset
Based on this I would speculate that for some reason the server doesn't get to each iMac in time so some try to boot from their internal drives. Anyone have an opinion on that?
Is there a way to set how long the computer will wait before giving up? Are there common switch configuration issues that might cause this? Unfortunately I don't have much to do with setting up the switches, but I can have our network admin make the needed changes, as long as I know what to ask for.
Thanks for any suggestions!
sean

Answer 1

Thanks for the reply. Keep in mind that I only used one method consistently throughout the entire lab, regardless of which method it was that time. I either booted them all by holding "N" or set them all via ARD. So what my question is, is why the inconsistency?
Booting with N held obviously booted them all up from the network. However setting them with ARD cause some to boot from the network and some not to. Then with the next reboot cycle (without having touched any startup disk settings) a completely different set of computers would boot from the network or not.
So the question, as you indicated at the end of your post, is really whether ARD is supposed to set the startup disk permanently or just for that boot. In either case it isn't working properly because some got set permanently and some didn't.
Oh well. I've actually abandoned NetBoot clients for now -- it was really a bit of an experiment for summer downtime.
Thanks again!