netTcpBinding
is bi-directional, so you don't need to do anything to specify the client's address.
The reason you have to specify it for wsDualHttpBinding
is because that binding establishes 2 HTTP channels (since HTTP isn't bi-directional) - one for the client to the service, and the second one for the service to the client.
So to answer your questions:
The address that will be used for the callbacks is the address of the client.
You don't need to change the callback address with
netTcpBinding
. Indeed, you wouldn't want to change it forwsDualHttpBinding
either - I think you meant how would you set it in code, and in this case you can't and don't need to.