Can anyone provide me a article for how to discover cmdb_ci_net_app_server ?

[LokeshN]

Even after having the community string still we are unable to discover this class devices cmdb_ci_net_app_server.

[dbook]

OOB there are no Patterns which write to the Network Appliance Hardware table. 

You will need to research the Device(s) and than would need to create a new pattern, a guide can be found here.