Intel® MPI Library User's Guide for Linux* OS
By default, Intel® MPI Library looks for a file called mpd.hosts. This file should contain a list of all available nodes on the cluster which can be used for your application. The format of the mpd.hosts file is a list of node names, one name per line. Blank lines and the portions of any lines that follow a # character are ignored.
You can specify the full path to this file by using the –f option.
When running under a supported job scheduler, using the –f option is unnecessary as the hosts will be determined by the scheduler.