Setup Elasticsearch Cluster over Oracle Virtualbox

Hello,

I am learning ES fro a while now, the standalone version is working without any issue but now I want to built a Cluster over Virtualbox and am failing again and again. This is what I have done up to now:

Oracle Virtual box on Windows 7 Host
Guest => CentOS 6.2 minimal, with ElasticSearch installed, SSH installed and different VMs are able to ping
on guest 2 network interfaces are configured: NAT and Host Only.

I want to use the 2nd interface (host only) for the cluster, it has DHCP enabled and my machines have IP addresses 192.168.56.102, 103, 104 and so on.

If I run the ES with default settings it works on eth0 i.e. 10.0.0.15 for all default by VBox. So i changed the "network.publish_host" to "eth1:ipv4" and getting the 2nd interface properly. But, the problem is that still all the VMs are working separately and not in a cluster.

http://localhost:9200/_nodes gives me
transport_address : inet[/192.168.56.102:9300] and
http_address : inet[/192.168.56.102:9200]

transport_address : inet[/192.168.56.103:9300] and
http_address : inet[/192.168.56.103:9200]

transport_address : inet[/192.168.56.104:9300] and
http_address : inet[/192.168.56.104:9200]

for each machine

http://localhost:9200/_cluster/health shows

status: yellow
no of nodes : 1

All machines can ping each other and I have tested the file transfer via scp too all is working

What am i missing?

Regards
Junaid