By default HDFS endpoints are specified as either hostnames or IP addresses. In either case HDFS daemons will bind to a single IP address making the daemons unreachable from other networks.
The solution is to have separate setting for server endpoints to force binding the wildcard IP address INADDR_ANY i.e. 0.0.0.0. Do NOT supply a port number with any of these settings.
Usually in most of cluster those settings are bind to 0.0.0.0 to make namenode listen to all interfaces.
In case - If you have any issues with Namenode communication [wrt load or communication issue between namenode-datanode or block report] then you need to go for tuning this properties. Please check the link for details -