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Exam 210-260 All Questions

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Exam 210-260 topic 1 question 178 discussion

Actual exam question from Cisco's 210-260
Question #: 178
Topic #: 1
[All 210-260 Questions]

If a switch port goes directly into a blocked state only when a superior BPDU is received, what mechanism must be in use?

  • A. STP BPDU guard
  • B. loop guard
  • C. STP Root guard
  • D. EtherChannel guard
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Suggested Answer: A 🗳️
The Root Guard feature can be enabled on all switch ports in the network off of which the root bridge should not appear (that is, every port that is not a root port , the port on each switch that is considered to be closest to the root bridge). If a port configured for Root Guard receives a superior BPDU, instead of believing the BPDU, the port goes into a root-inconsistent state. While a port is in the root-inconsistent state, no user data is sent across it. However, after the superior BPDUs stop, the port returns to the forwarding state.

The BPDU Guard feature is enabled on ports configured with the Cisco PortFast feature. The PortFast feature is enabled on ports that connect to end-user devices, such as PCs. It reduces the amount of time required for the port to go into forwarding state after being connected. The logic of PortFast is that a port that connects to an end-user device does not have the potential to create a topology loop. Therefore, the port can go active sooner by skipping STPs listening and learning states, which by default take 15 seconds each. Because these PortFast ports are connected to end-user devices, they should never receive a BPDU.
Therefore, if a port enabled for BPDU Guard receives a BPDU, the port is disabled.
Reference:
https://learningnetwork.cisco.com/thread/4575

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max80
4 years, 11 months ago
stats: block - it's root guard disable - it's bpdu guard
upvoted 1 times
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jocarul
4 years, 11 months ago
"STP root guard" is ok
upvoted 3 times
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piccione17
5 years ago
Answer is root guard (C)
upvoted 2 times
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ciscotesting22
5 years, 8 months ago
should be C
upvoted 2 times
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