Practice Test Geeks(STP) Spanning Tree Protocol Practice Test
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Advanced Features and Variants Flashcards

7 cards from real STP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Advanced Features and Variants flashcards as text

  1. What is the purpose of Loop Guard in STP?

    Answer: To protect against loops caused by unidirectional link failures on non-designated ports

    Loop Guard moves a port to loop-inconsistent blocking state if BPDUs stop arriving on a port expected to receive them, preventing loops from unidirectional failures.

  2. Which feature detects unidirectional fiber link failures at the physical layer, complementing Loop Guard at the STP layer?

    Answer: UDLD (UniDirectional Link Detection)

    UDLD sends periodic echo messages; if no reply is received, it identifies the link as unidirectional and can shut the port down.

  3. What does enabling BPDU Filter on a PortFast-enabled port do?

    Answer: Suppresses sending and ignores receiving BPDUs on that port

    BPDU Filter prevents the port from sending or processing BPDUs, effectively removing it from STP participation — use with caution.

  4. In Rapid PVST+, what type of port can transition directly to Forwarding without going through Discarding and Learning states?

    Answer: Edge Port (PortFast-enabled) when link comes up

    Edge ports (PortFast) skip Discarding and Learning, transitioning immediately to Forwarding because they connect to end devices with no downstream bridges.

  5. What happens to a PortFast-enabled port if BPDU Guard is active and a BPDU is received?

    Answer: The port is placed in err-disabled state immediately

    BPDU Guard immediately err-disables the port upon receiving any BPDU, requiring manual or auto-recovery intervention.

  6. How does STP handle a topology change in RSTP compared to classic 802.1D?

    Answer: RSTP flushes MAC tables and sends TC BPDUs for twice the Hello time; 802.1D propagates TCNs to the root first

    RSTP originates TC BPDUs directly and flushes MAC addresses for twice the Hello time, while 802.1D sends TCNs upstream to the root which then sets the TC flag for Forward Delay duration.

  7. Which MSTP concept describes the role of an MST region boundary port connecting to another region or a legacy STP bridge?

    Answer: Boundary Port

    A boundary port is an MST port that connects to a switch in a different MST region or running legacy STP/RSTP.