Well your configuration is all wrong.
First, your two Liferay nodes should form a proper cluster and be fronted by a load balancer.
From the browser's perspective, the CAS tokens are tied to the main site URL, not "node 1" or "node 2".
On the back end, the node will redirect to CAS for authentication and the incoming CAS token cookies are tied to the main site URL so they are visible in both nodes.
In your current configuration, CAS has approved the token based on the URL for node 1, but this is not going to be the same URL on node 2 so the CAS token cookie will not be handed to node 2.
Now if these are not Liferay nodes in a cluster, then I think your configuration is still off. The CAS token cookie must be bound to a less specific URL such as http://example.com so it would be visible to all subdomains; if you've bound the CAS token cookie to http://node1.example.com then the cookie cannot be passed to http://node2.example.com because of the different domain.
