Accessing Content Fragment using Dispatcher URL

We are building content fragments and exposing to Mobile App.

Able to get the CF json output when we use direct publish URL  https://publishURL/api/assets/abc-fragment.json

But when we use dispatcher URL(setup for our website) https://sitedomain/api/assets/abc-fragment.json we are getting page not found.

We do not want to use direct publish to expose Content fragments to Mobile App.

So do we have to configure any other settings or dispatcher rules to expose content fragment using a dispatcher vhost domain? 

Appreciate inputs.

Thanks.