Based on the provided network diagram (BID: 32768.0c-00-00-0a-01-01, 32768.0c-00-00-0a-01-02, 32768.0c-00-00-0a-00-03, 32768.0c-00-00-0a-00-04), which of the following statements is true regarding…

Question

Options

• AThe G0/0/3 port of SW3 will be changed from DPD to AP port.
• BThe G0/0/2 port of SW4 maintains its original port role.
• CThe G0/0/3 port of SW4 will be changed from AP port to DP port.
• DThe G0/0/5 port of SW3 maintains its original port role.

• A
  83% (24)
• B
  3% (1)
• C
  3% (1)
• D
  10% (3)

Explanation

Option A is correct because when a topology change triggers STP reconvergence in this network, SW3's G0/0/3 port receives a superior BPDU from a neighboring bridge, causing it to lose the Designated Port election on that segment and transition to Alternate Port (AP) - the RSTP blocking role for a port that has a viable but non-preferred path to the root bridge. Option B is wrong because SW4's G0/0/2 is directly impacted by the same reconvergence event, so its role changes rather than staying stable. Option C has the direction reversed: the port role transition on SW4's G0/0/3 goes in the opposite direction stated, because the bridge that wins the Designated Port election on that segment changes as a result of the new topology. Option D is wrong because SW3's G0/0/5 is similarly caught up in the reconvergence and cannot maintain its original role.

Memory tip: When tracing STP role changes after a topology event, use the phrase "Lower wins, loser blocks." - the bridge with the lower BID wins the Designated Port role on each segment, and the other bridge's port becomes the Alternate Port. Start at the root bridge and work outward, segment by segment, to lock in each port's role before the topology change and after.

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