Has anyone made any progress with this issue? We’re facing the same thing now – our DeployStudio image works fine (made from a MacBook Air that’s 3 weeks old, so it’s 10.7.3 based), but when we started getting ready for our changeover to Casper, the net booting stopped.
I believe our problem is related to the multiple subnets – I have a test NetBoot server at my desk and I can net boot affected machines when they’re in the same subnet, but the second I change to the (very much working in every other way) Netboot server in our data center, I just get the Apple logo, then the globe, then the “no” symbol, all in rapid succession. This is from the same NetBoot set that works on my test server.