Question $26$

$1$ pts

Which are accurate statements about the OSI model? For communication "down the stack" for example, from the transport layer to the network layer

The protocol$-$data unit of the lower layer is the service$-$data unit of the upper layer.

The protocol$-$data unit of the lower layer is the protocol$-$data unit of the upper layer.

The service$-$data unit of the lower layer is the service$-$data unit of the upper layer.

The service$-$data unit of the lower layer is the protocol$-$data unit of the upper layer.

Question $27$

$1pts$

In the OSI model, what is the service$-$data unit of a lower layer?