All this is likely the case because Network Objects is in Beta. As and when that's no longer the case, the relevant documentation and tools get promptly updated, in my experience.
@Kiran_Oddiraju the documentation I linked in my initial reply makes it clear that both FQDN and Wildcard FQDN are supported. For use within the API substitute "type":"fqdn" within the cURL example provided
I've got a lot of questions, too. I see an example of how to add (POST) a network object. Would be nice to have some examples of how to query and delete test objects, too. I'm using cURL on Windows and Linux.