I am trying to run the following command from a host1 for a
host2(202.165.250.110)

Host#1
[root@localhost]# ssh@202.156.250
user@202.165.250.110's password:

when I enter the correct root password of the system it's giving the following error message.

Permission denied, please try again.

Tell me please. What is that I missing??

It doesn't look like your root account
Try ssh root@your_ip

And check if you haven't got PermitRootLogin no set in your sshd_config

It simply tells that the password is wrong. Double check the syntax of the ssh command. If you omit the username (e.g. ssh 202.165.250.110) it try to connect with the same user as you are logged in on Host1. If you specify the user (e.g. ssh user@202.165.250.110) you are sure to log on Host2 as user.

yes its working when i remove user@ from the command. But I want to run it with the rsa key-generation module in the following manner,

host1 ~# ssh-keygen -t rsa
host1 ~# scp .ssh/id_rsa.pub user@host2:host1_id_rsa.pub
host1 ~# ssh user@host2

over here when i enter the root password of host2 it's giving me an error message of
Permission denied, please try again. Which i don't understand why its doing so? I then want to run the following commands.

host2 ~$ mkdir .ssh
host2 ~$ chmod 700 .ssh
host2 ~$ cd .ssh
host2 .ssh$ mv ../host1_id_rsa.pub ./
host2 .ssh$ cat host1_id_rsa >> authorized_keys
host2 .ssh$ chmod 600 authorized_keys

The key you want to generate is for root or for user? Anyway, to be sure specify root@host2 when you want to login as root, user@host2 when you want to login as user. If the key is for user, you have to login as user, otherwise you have to change ownership after creating files as root.

Thanks a lot I got it running cuz of your help