The Cplant utilities display host names for the compute nodes that indicate what physical part of the machine they are in. For example the cluster ross is composed of racks of 32 nodes and the host name displayed for a compute node includes the rack number and the number of the node within the rack.
The utilities derive these hostnames from the cplant-map file. The format of the file is a list of host names in physical node number order.
The location of the cplant-map file can be specified with the environment variable or site file entry NODE_NAMES_FILE.