The DHCP_IP_CLUSTER structure is not used.

 typedef struct _DHCP_IP_CLUSTER {
   DHCP_IP_ADDRESS ClusterAddress;
   DWORD ClusterMask;
 } DHCP_IP_CLUSTER,
  *LPDHCP_IP_CLUSTER;

ClusterAddress: This is of type DHCP_IP_ADDRESS, a DWORD.

ClusterMask: This is of type DWORD.