@Rajashree
For the application stack questions, please refer to documentation beginning from Application Stacks Overview
For the questions about what's being discovered, please refer to documentation starting at What We Collect
You control which subnets are being discovered, and as such also whether you limit its scope to the datacenters or to include subsets of your client environment, which may be important if some of these contribute to business critical services.
Please don't hesitate to elaborate further on your questions if the above is insufficient.
Thanks,
