While creating a multinode cluster, my nodes are unable to identify all the nodes in the cluster. 
Only the *last added'  node is visible when I do:
 ./nodetool -h localhost ring

I am trying to create a 4 nodes cluster. On starting the seed node, the above command shows just itself(ok.. good), then when I start the 2nd node the first one disappears & there is only 2nd visible in the ring. On starting 3rd one, just the 3rd one remains.

In cassandra.yaml of each node, I configured the listen_adress equal to ip address of that node & for seeds I just put the ip address of 1st node everywhere.

Can anyone point to me what may be causing this ?