Nodemanager does not register with RM using the fully qualified hostname

If the hostname is misconfigured to not be fully qualified ( i.e. hostname returns foo and hostname -f returns foo.bar.xyz ), the NM ends up registering with the RM using only "foo". This can create problems if DNS cannot resolve the hostname properly.

Furthermore, HDFS uses fully qualified hostnames which can end up affecting locality matches when allocating containers based on block locations.