200-301 · Question #1179
What are two features of PortFast? (Choose two.)
The correct answer is A. Convergence is fast after a link failure. C. Ports transition directly from the blocking state to the forwarding state.. PortFast is a Cisco switch feature that enables rapid Spanning Tree Protocol (STP) convergence on edge ports by transitioning them directly to the forwarding state, and it is part of overall fast convergence strategies.
Question
What are two features of PortFast? (Choose two.)
Options
- AConvergence is fast after a link failure.
- BSTP loops are mitigated for uplinks to other switches.
- CPorts transition directly from the blocking state to the forwarding state.
- DPorts operate normally without receiving BPDUs.
- EPorts that connect to the backbone automatically detect indirect link failures.
How the community answered
(44 responses)- A93% (41)
- D5% (2)
- E2% (1)
Why each option
PortFast is a Cisco switch feature that enables rapid Spanning Tree Protocol (STP) convergence on edge ports by transitioning them directly to the forwarding state, and it is part of overall fast convergence strategies.
While PortFast primarily speeds up initial port state transitions, features like UplinkFast and BackboneFast work in conjunction with STP to improve convergence time after link failures, and PortFast is part of the overall rapid STP convergence strategy on edge ports.
PortFast is designed for end-device ports, and applying it to uplinks to other switches can create STP loops if not properly managed, as it bypasses loop prevention mechanisms.
PortFast causes a switch port to transition immediately from the blocking or listening state to the forwarding state, bypassing the typical listening and learning states of STP to provide immediate network access for end devices.
Ports configured with PortFast still receive and process BPDUs; if a BPDU is received, PortFast is disabled on that port to prevent loops, indicating it does not operate normally without receiving them.
PortFast does not automatically detect indirect link failures; features like UplinkFast and BackboneFast are designed for such scenarios in STP.
Concept tested: Spanning Tree PortFast features
Source: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/3se/consolidated/configuration_guide/b_consolidated_3850_3se_config_guide/b_consolidated_3850_3se_config_guide_chapter_01000.html#concept_06C787265F9341409F36FB1421448A43
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