“definst” is the default Application Instance.
If you publish to:
rtmp://[wowza-address]:1935/test
You are actually publishing
rtmp://[wowza-address]:1935/test/definst
If you add an explicit Application Instance part to the rtmp url, that is what will be used:
rtmp://[wowza-address]:1935/test/instance1
A subscribing client will have to also connect to that instance to view the stream.
Richard