get https://e-{networkId}.adzerk.net/udb/{networkId}/interest/i.gif?userKey=&interest=
This pixel endpoint adds an Interest to a specific UserKey via query params. Calling this endpoint multiple times will add multiple Interests.
Interests are also called Flight Categories. To see what Interests have already been created in the system, you'll want to use the List Network Categories Endpoint or List Flight Categories Endpoint.
Note that the user key supplied in the
userobject will override a user key set via theazkcookie.