Error : WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!

If you have reinstalled Linux or UNIX with OpenSSH, you will get the bellow error. (or else changes in hostname and ip address)
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Error
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[root@TESTBEDMRPDB opt]# ssh root@172.21.17.43
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
8c:32:d8:2c:94:18:4f:7f:7f:2a:15:60:4d:6f:50:79.
Please contact your system administrator.
Add correct host key in /root/.ssh/known_hosts to get rid of this message.
Offending key in /root/.ssh/known_hosts:3
RSA host key for 172.21.17.43 has changed and you have requested strict checking.
Host key verification failed.
lost connection
[root@TESTBEDMRPDB opt]#

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Solution :
In destination machine add as below.
to known host


[root@TESTBEDMRPDB opt]# ssh-keygen -R 172.21.17.43
/root/.ssh/known_hosts updated.
Original contents retained as /root/.ssh/known_hosts.old
[root@TESTBEDMRPDB opt]#


and / or

may be check below

#TESTBEDQCMRPGDB.PABNG.COM,172.21.17.43 ssh-rsa