Final answer:
The RDT 3.0 protocol with alternating-bit will fail with out-of-order data frames because it relies on sequential order to function properly. The correct answer is d) Out-of-order data frames.
Step-by-step explanation:
The question relates to the RDT 3.0 protocol and scenarios where the alternating-bit protocol could fail. Among the options provided, the scenario where the alternating-bit protocol will not work correctly is d) Out-of-order data frames.
The alternating-bit protocol relies on the agreed sequential order of frames to track successfully received packets and acknowledgements; thus, out-of-order frames break this assumption and the protocol can't handle such cases naturally.
The RDT 3.0 protocol is an example of the alternating-bit protocol that is used to ensure reliable data transfer between a sender and receiver in an unreliable network. However, if the underlying network is unreliable, there are scenarios in which the alternating-bit protocol will not work correctly.
One such scenario is 'lost acknowledgement frames'. In this case, the receiver does not receive the acknowledgement frame sent by the sender, and therefore, the sender assumes that the last data frame was lost and retransmits it. But if the data frame was actually received by the receiver and the acknowledgement frame was lost, the receiver will mistakenly discard the duplicate data frame.