TNS-12543: TNS:destination host unreachable in CentOS

[oracle@jcraju admin]$ tnsping proddbp 9

TNS Ping Utility for Linux: Version 12.2.0.1.0 - Production on 13-JUL-2018 08:25:46

Copyright (c) 1997, 2016, Oracle.  All rights reserved.

Used parameter files:

Used TNSNAMES adapter to resolve the alias

Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = jcraju.prod.com)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = proddb)))

TNS-12543: TNS:destination host unreachable

Solution:

As a root user stop iptables service

--> service iptables save

--> service iptables stop

--> chkconfig iptables off

check tnsping if it's not working

check selinux status and change it to disabled

#cat /etc/selinux/config

SELINUX=disabled

#reboot server

Check firewall status and stop it

--> systemctl status firewalld

--> systemctl stop firewalld

[oracle@jcraju ~]$ tnsping proddbp 4

TNS Ping Utility for Linux: Version 12.2.0.1.0 - Production on 16-JUL-2018 06:54:08

Copyright (c) 1997, 2016, Oracle.  All rights reserved.

Used parameter files:

Used TNSNAMES adapter to resolve the alias

Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = jcraju.prod.com)(PORT = 1521)) (CONNECT_DATA = (SERVICE_NAME = proddb)))

OK (10 msec)

OK (0 msec)

OK (10 msec)

OK (0 msec)