642-811 Building Cisco Multilayer Switched Networks (BCMSN) Practice Test

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642-811 Building Cisco Multilayer Switched Networks (BCMSN)

Note 1: 642-811 Exhibit and all related diagrams are not shown in demo questions.
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Demo Question 3.

You are a network troubleshooter and you've been called into the EliteCertify to manually put a switch port back into service after it was put into the error disabled state upon receipt of Spanning Tree messages. Which of the following STP features puts a switch port into an error-disabled state when it receives Spanning Tree data messages?

A. BDPU Filtering
B. Root Guard
C. BDPU Guard
D. Port Fast
E. Loop Guard
F. None of the above

Display Answer

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Answer: C

Explanation: Understanding BPDU Guard The BPDU guard feature can be globally enabled on the switch or can be enabled per interface, but the feature operates with some differences. At the global level, you can enable BPDU guard on Port Fast-enabled ports by using the spanning-tree portfast bpduguard default global configuration command. Spanning tree shuts down ports that are in a Port Fast-operational state. In a valid configuration, Port Fast-enabled ports do not receive BPDUs. Receiving a BPDU on a Port Fast-enabled port signals an invalid configuration, such as the connection of an unauthorized device, and the BPDU guard feature puts the port in the error-disabled state. Reference: http://www.cisco.com/en/US/products/hw/switches/ps5206/products_configuration_guide_chapter09186a00801 7