I did see an article with some users having the unknown computers issue. I do not get the unknown entries after the first PXE boot. I import my computer with a specific name. That computer does remain in its collection after one successful PXE boot. I never find those computers or unknown computers in the "all desktop and server clients" collection.
I did find some additional information from my troubleshooting. If I delete the computer from its SCCM deployment collection then re-add it by importing the Computer information, it will sometimes receive the DHCP request and boot into PXE. This could take a day of the computer being out of SCCM before I can add it back in to make it work. This sounds like the unknown computer issue but does not always work.
Is there a certain amount of time the computer need to be out of SCCM before it can be re-added to get the DHCP request again? Somehow I get the feeling I am missing a setting in SCCM that tells it to always accept DHCP request from clients.
Thanks,