Cisco UCS servers sending a DHCP client-id that I can't pre-determine?

Hi all,

Weird one that I haven't encountered. I have some Cisco UCS C240 M5SX's that are sending a 36 character string as their DHCP client-id rather than their MAC address as I would expect. This is making it hard to deliver configs via PXE, do DHCP reservations, etc before hand.

Does anyone know where this identifier is coming from? They all seem to start with "b6220feb00020000" and then a changing 20 character string that tends to start with "ab".