Nodeapps are a standard set of oracle application services which are started automatically for RAC.
Node apps Include:
1) VIP.
2) Oracle Net listener.
3) Global Service Daemon.
4) Oracle Notification Service.
Nodeapp Services run on each node of the cluster and will switched over to other nodes through VIP during the failover.
#srvctl start nodeapps -n node_name — Starts GSD, VIP, listener & ONS
#srvctl stop nodeapps -n node_name [-r] — Stops GSD, VIP, listener & ONS
#srvctl status nodeapps -n node_name
#srvctl config nodeapps -n node_name [-a] [-g] [-o] [-s] [-l]
-a Display VIP configuration
-g Display GSD configuration
-s Display ONS daemon configuration
-l Display listener configuration