If you use an interfaces file, it must include entries for the cluster server and all instances.
instance_name: master network_protocol machine_name port_number query network_protocol machine_name port_number . . . cluster_server_name query network_protocol ether machine_name port_numberwhere:
ase1 master tcp ether blade1 19786 query tcp ether blade1 19786 ase2 master tcp ether blade2 19786 query tcp ether blade2 19786 ase3 master tcp ether blade3 19786 query tcp ether blade3 19786 mycluster query tcp ether blade1 19786 query tcp ether blade2 19786 query tcp ether blade3 19786