350-401 · Question #629
Refer the exhibit. Which configuration elects SW4 as the root bridge for VLAN 1 and puts G0/2 on SW2 into a blocking state?
The correct answer is B. SW4(config)#spanning-tree vlan 1 priority 0. The question asks for the configuration to make SW4 the root bridge for VLAN 1 and implicitly cause a specific port on SW2 to block due to the STP election process.
Question
Refer the exhibit. Which configuration elects SW4 as the root bridge for VLAN 1 and puts G0/2 on SW2 into a blocking state?
Exhibits
Options
- ASW4(config)#spanning-tree vlan 1 priority 0
- BSW4(config)#spanning-tree vlan 1 priority 0
- CSW4(config)#spanning-tree vlan 1 priority 32768
- DSW4(config)#spanning-tree vlan 1 priority 32768
How the community answered
(54 responses)- A11% (6)
- B43% (23)
- C17% (9)
- D30% (16)
Why each option
The question asks for the configuration to make SW4 the root bridge for VLAN 1 and implicitly cause a specific port on SW2 to block due to the STP election process.
This option is identical to B, but without the exhibit and full context, it's chosen as not the primary correct option in the provided answer key.
Setting the Spanning Tree Protocol (STP) priority to 0 for VLAN 1 on SW4 ensures it has the lowest possible priority (default is 32768) and will be elected as the root bridge. Once SW4 is the root, other switches like SW2 will determine their root and designated ports, and an alternative port will enter a blocking state to prevent loops.
Setting the priority to 32768 is the default priority for VLAN 1, which means SW4 would likely not become the root bridge unless all other switches have a higher priority or a higher MAC address if priorities are equal.
Setting the priority to 32768 is the default and would not guarantee SW4 as the root bridge.
Concept tested: Spanning Tree Protocol (STP) root bridge election
Source: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/12-2/31sg/configuration/guide/config/spntree.html
Topics
Community Discussion
No community discussion yet for this question.