update /etc/hosts and system level

Change-Id: If14e63ad26c5a3fc915680c8e3569dfba526297a
diff --git a/classes/cluster/virtual-mcp-ocata-ovs/openstack/init.yml b/classes/cluster/virtual-mcp-ocata-ovs/openstack/init.yml
index cd42a02..46f4365 100644
--- a/classes/cluster/virtual-mcp-ocata-ovs/openstack/init.yml
+++ b/classes/cluster/virtual-mcp-ocata-ovs/openstack/init.yml
@@ -116,6 +116,7 @@
     mongodb_shared_key: eoTh1AwahlahqueingeejooLughah4tei9feing0eeVaephooDi2li1TaeV1ooth
   linux:
     network:
+      purge_hosts: true
       host:
         prx:
           address: ${_param:openstack_proxy_address}