Had the network team add icmp echo inbound to the DNS servers from the drac VLAN, and dynamic dns now works for the dracs.
I have idrac8 and idrac7's, though it occurs with idrac6 and 5 as well.  Under no circumstances can I get the dracs to register themselves in DNS I have confirmed that TCP 53 & UDP 53 are open, and the Microsoft DNS zone has non-secure and secure registrations are allowed.  The vlan the dracs are on has dhcp enable and the dracs grab their dns servers from the dhcp server. I update the firmware on one of the idrac8's and even put it on the vlan as the dns servers, and still dns registration.
Idrac DNS registration