Maybe a dumb question that I should know.... During development how do I make my test machine unknown again?

delete it from the SCCM database (search for it in All Systems, select it, right click, delete) then restart the Windows Deployment Service My step by step SCCM Guides I'm on Twitter > ncbrady

That is the problem it is not in any collection. I have done what you sugested but it still thinks it is there....

restarting the wds service is not necessary but it helps if the wds cache time out period (default 60 minutes) hasnt timed out yet, if the computer is still 'known' then search for its MAC address in a collection (create a direct membership query, search for the MAC address), it should show up in that test collection, then delete it and try a pxe boot again My step by step SCCM Guides I'm on Twitter > ncbrady

That was it!! Found another record with MAC address. THANKS!!