Cluster with 4 Pi's running Raspbian master node not connecting to slave nodes

My master node (Endeavour) - 10.0.0.1 works when getting hostname using `mpiexec host -10.0.0.1 hostname` from the slave nodes except whenever I try to get the hostname of the slave node from my master it is just blank. I cannot get any hostname from any slave that it either isn't local to or isn't the master.

For eg, I cannot get node 2's hostname from node 3 or the master node, I have to physically log onto node 2 and get it.