I have a Server 2008 R2 DHCP Failover Cluster that serves two VLANs - an office network and a guest WiFi network. Both of the members of the failover cluster are virtual machines (ESXi) and use the iSCSI Initator inside the VM for their shared storage. Each node in the cluster also runs other FO Cluster services that are working fine.
However, with the DHCP service, in the past 3 weeks it has started only ever remembering one of its DHCP address offered. This is a real problem because it basically starts offering in-use addresses causing IP conflicts all over the network. Every now and again it will go and fill up its table with "BAD_ADDRESS" entries to cover the in-use IP's that it finds, but then they go away as well.
This is what the scope leases look like at the moment. There's only one non-reserved lease listed:
When I connect my iPhone to the network, it takes literally about 45 seconds to get an IP address:
And when it does, it's not showing up in the lease list anywhere. Which means that next time someone else connects a new device, they will end up with the same IP address and then a BAD_ADDRESS will be marked in the list - until the next device connects when the whole thing will be lost and it will go and re-mark them all:
The only thing I can think of is that these cluster members used to be Hyper-V members and were migrated to ESXi at about the same time these issues started occuring - but I can't be 100% sure.