In Stop-and-Wait ARQ, if a transmitted data frame is damaged and discarded by the receiver, how does the sender detect the loss?
In Stop-and-Wait ARQ, a timeout can detect a missing acknowledgment. In variants that use NAKs, the receiver can explicitly report a detected damaged frame. Thus A and B describe valid loss/error-detection mechanisms.
In Go-Back-N (GBN) ARQ, what action does the receiver take when frame 4 arrives corrupted, but subsequent frames 5 and 6 arrive error-free?
Because GBN receiver window size is 1, the receiver accepts frames strictly in sequence. Any out-of-order frame (5, 6) is silently discarded.
In an 802.3 Ethernet network, if two stations transmit simultaneously causing a collision, what special signal is transmitted to ensure all stations detect the collision?
Classic shared Ethernet using CSMA/CD sends a jam signal so the collision is recognized by stations, and the involved stations then apply binary exponential backoff before retrying. Thus A and B are correct.
What is the primary function of the IEEE 802.1D Spanning Tree Protocol (STP) running on network bridges and switches?
STP disables redundant physical paths logically to maintain a loop-free tree topology, eliminating broadcast storms and multiple frame copies.
Which switching method on a Layer-2 Ethernet switch buffers the first 64 bytes of an incoming frame to inspect the header and filter out collision runts before forwarding?
Fragment-Free switching waits for the first 64 bytes to avoid forwarding collision fragments, while Store-and-Forward receives the complete frame and validates it (including FCS) before forwarding. Thus A and B are correct.