Several people have asked me how the unknown computer support in ConfigMgr R2 works. I can honestly say I don't know because I haven't had a chance to try it yet. (I've been busy on other things.) Fortunately, Steve Rachui has had time to explore the new capabilities and has posted two blog entries explaining how to use it:
Just be careful when using mandatory advertisements with the R2 unknown computer support: those will deploy a new OS to any unknown computer. There are two ways that you can avoid accidentally reimaging a machine:
So there's one scenario where you might want to continue using the MDT 2008 unknown computer support, even if you are running ConfigMgr R2: if you want to respond to unknown computers with a mandatory advertisement but only on a certain subnet (e.g. only in a staging room). You can edit the MDT PXEFilter.vbs script to do such filtering, but R2 don't offer any filtering.