300-420 · Question #156
300-420 Question #156: Real Exam Question with Answer & Explanation
The correct answer is A: PortFast. {"question_number": 2, "correct_answer": "A", "explanation": "PortFast should be applied to Gi1/0/1-10 to optimize STP convergence time on access-layer ports connected to end devices (PCs, servers, printers). Without PortFast, an STP port transitions through Blocking → Listening
Question
Refer to the exhibit. An architect reviews the low-level design of a company's enterprise network and advises optimizing the STP convergence time. Which functionality must be to Gi1/0/1-10 to follow the architect's recommendation?
Options
- APortFast
- Broot guard
- CUplinkFast
- DBPDU guard
Explanation
{"question_number": 2, "correct_answer": "A", "explanation": "PortFast should be applied to Gi1/0/1-10 to optimize STP convergence time on access-layer ports connected to end devices (PCs, servers, printers). Without PortFast, an STP port transitions through Blocking → Listening (15s) → Learning (15s) → Forwarding, causing a 30-second delay before the port becomes usable. PortFast bypasses the listening and learning states, bringing the port immediately to forwarding state, which dramatically reduces convergence time for end-host connections. Root Guard (B) prevents unauthorized switches from becoming the root bridge and is applied on designated ports facing potential rogue switches-not end-device ports. UplinkFast (C) accelerates convergence on uplink ports toward the distribution layer when a primary uplink fails. BPDU Guard (D) is a complementary security feature often paired with PortFast that shuts down a PortFast-enabled port if it receives a BPDU, but BPDU Guard alone does not speed up convergence.", "generated_by": "claude-sonnet", "llm_judge_score": 4}
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