NodeManager getting stopped after some time

[#1]

After starting the nodemanager, it was getting stopped when tried to connect with one of the resource managers by throwing the below.

2016-07-27 11:03:03,820 INFO  retry.RetryInvocationHandler (RetryInvocationHandler.java:invoke(144)) - Exception while invoking registerNodeManager of class ResourceTrackerPBClientImpl over rm2 after 17 fail over attempts. Trying to fail over after sleeping for 34825ms.
java.net.ConnectException: Call From dev5.exp.caspian.rax.io to dev3.exp.caspian.rax.io:8031 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused

[#2]

Please check on dev3.exp.caspian.rax.io node to see if any process is listening on port 8031. If it is the case, check if you can establish connection to that port from dev5.exp.caspian.rax.io. It looks like either a network issue or the RM process not running.

[#3]

But there is no process running on 8031

[dev3.exp ~]$ sudo netstat -nlp| grep 8031
[dev3.exp ~]$

[#4]

Is there any firewall is running on system?