The interface on core2 for netapp-d was admin shutdown. I'm sure there was a reason at one point, can't recall it now. Probably something to do with the bonding.
This killed a number of build machines.
I've pulled up the interface on core2 for now.
I'm guessing netapp-c is single-homed on core2 and netapp-d was single-homed on core1.
They are dual-homed now, tested failover as well.