@ESJosephPrinz,
I don't believe there is currently a way to get the DNS name of the host on the Network Mapper results, however you can export that so you can create a simple PowerShell or Python script or whatever to attempt to resolve the IP and run through your export.
As to testing the agent, I've not found a good way outside of confirming Network Mapper results with your endpoint results through exports and scripts to ensure that the agents are actually active across your device fleet. You can use wildfire.paloaltonetworks.com/publicapi/test/pe to test a detection on the endpoint and script that download and execution if you want to validate Cortex is actually working, but if an endpoint becomes unregistered it obviously won't trigger anything except on the functional hosts, so a review is what I recommend.
I have had agents become unregistered from the portal, albeit on a much lesser amount now than previously, that you won't know about unless you review your endpoint list and actively check for "Connection Lost" and manually reviewing your host list. This used to happen much more frequently, but we still run across it occasionally.
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