Refer to the exhibit. What is the result when a switch that is running PVST+ is added to this network?

Question

Exhibits

Options

• ADSW2 operates in Rapid PVST+ and the new switc operates in PVST+
• BBoth switches operate in the PVST+ mode
• CSpanning tree is disabled automatically on the network
• DBoth switches operate in the Rapid PVST+ mode.

• A
  81% (25)
• B
  3% (1)
• C
  10% (3)
• D
  6% (2)

Explanation

Explanation

When a switch running PVST+ is added to a network where an existing switch (DSW2) is running Rapid PVST+, the two protocols operate independently per-port - the Rapid PVST+ switch (DSW2) detects the older PVST+ neighbor and falls back to 802.1D STP behavior on that specific port, while each switch continues running its own configured version, making A correct.

Why the distractors are wrong:

• B is wrong because DSW2 is running Rapid PVST+ and does not downgrade its entire operation to PVST+; it only uses legacy compatibility on the connected port.
• C is wrong because STP is never automatically disabled when mismatched versions connect - this would be a dangerous assumption and does not reflect actual switch behavior.
• D is wrong because a PVST+ switch cannot be automatically upgraded to Rapid PVST+; it must be manually configured to do so.

Memory Tip

Think of it like a language conversation - if you speak advanced English and someone speaks basic English, you slow down to accommodate them on that conversation, but you haven't forgotten how to speak advanced English. Rapid PVST+ accommodates PVST+, but each switch keeps its own STP version.

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