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350-001 · Question #101

Which two of these are used in the selection of a root bridge in a network utilizing Spanning Tree Protocol IEEE 802.1D? (Choose two.)

The correct answer is B. bridge ID priority D. bridge ID MAC address. The root bridge of the spanning tree is the bridge with the smallest (lowest) bridge ID. Each bridge has a unique identifier (ID) and a configurable priority number; the bridge ID contains both numbers. To compare two bridge IDs, the priority is compared first. If two bridges…

Layer 2 Technologies

Question

Which two of these are used in the selection of a root bridge in a network utilizing Spanning Tree Protocol IEEE 802.1D? (Choose two.)

Options

  • ADesignated Root Cost
  • Bbridge ID priority
  • Cmax age
  • Dbridge ID MAC address
  • EDesignated Root Priority
  • Fforward delay

How the community answered

(33 responses)
  • B
    88% (29)
  • C
    3% (1)
  • E
    6% (2)
  • F
    3% (1)

Explanation

The root bridge of the spanning tree is the bridge with the smallest (lowest) bridge ID. Each bridge has a unique identifier (ID) and a configurable priority number; the bridge ID contains both numbers. To compare two bridge IDs, the priority is compared first. If two bridges have equal priority, then the MAC addresses are compared. For example, if switches A (MAC=0200.0000.1111) and B (MAC=0200.0000.2222) both have a priority of 10, then switch A will be selected as the root bridge. If the network administrators would like switch B to become the root bridge, they must set its priority to be less than 10.

Topics

#STP root bridge election#bridge ID priority#bridge ID MAC address#IEEE 802.1D

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