For an example of how the Ai Rayswitch node can be helpful, see the reducing noise topic in the Image Based Lighting section (although note that the precise method described there would not be necessary if you use the Ai Skydome light instead of the Ai Sky).

Camera

Shadow

Diffuse Reflection 

Specular Reflection

Diffuse Transmission

Specular Transmission

Volume

 

 

 

Pepe model by Daniel M. Lara (Pepeland)