Exam JN0-351 topic 1 question 63 discussion

A. RSTP alternate ports block traffic while receiving superior BPDUs from a neighboring switch. Correct. C. Alternate ports provide a higher cost path to the root bridge. Correct - if they were a lower cost to the root bridge they would not be an alternate port but a root port.

Alternate Port : Alternate ports block traffic while receiving superior BPDU from a neighboring switch. Is an alternate, higher cost, path to the root. (Secondary root port)

A. RSTP alternate ports block traffic while receiving superior BPDUs from a neighboring switch. B. RSTP alternate ports provide an alternate lower cost path to the root bridge.

Incorrect Options: C. RSTP alternate ports provide an alternate higher cost path to the root bridge. This is incorrect because alternate ports usually provide a lower-cost or equal-cost path compared to the current active port. D. RSTP alternate ports are active ports used to forward frames toward the root bridge. This is incorrect because alternate ports do not forward traffic. They are in the blocking state and only become active when the primary port fails.

The two correct characteristics of RSTP (Rapid Spanning Tree Protocol) alternate ports are: A. RSTP alternate ports block traffic while receiving superior BPDUs from a neighboring switch. This is correct because alternate ports receive superior BPDUs (Bridge Protocol Data Units) from the root bridge and remain in a blocking state, ready to take over if the root or designated port fails. B. RSTP alternate ports provide an alternate lower cost path to the root bridge. This is also correct. The alternate port offers a backup path to the root bridge, and it typically provides a lower-cost path than other potential paths. If the primary designated port fails, the alternate port can quickly become the active path.

A,C are correct