Could some one explain the topology of alerts. Within NagiosQL commsioning

I seem to be having issues where by the services of a host are alerting but some of my deivces are just routers that I want to know if they are down and up.

I have hosts configured to a host template then goes to the generic-host template
i have services configured to a service template local-service then to generic service.

Where are the alerts configured?

Thanks
lee