When using Rapid PVST+, which command guarantees the switch is always the root bridge for VLAN 200?
When using Rapid PVST+, which command guarantees the switch is always the root bridge for VLAN 200?
To guarantee a switch is always the root bridge for VLAN 200 in a Rapid PVST+ environment, use the command 'spanning-tree vlan 200 root primary'. This command sets the switch's priority to a lower value than any other switch currently detected in the network, ensuring it becomes the root bridge for that VLAN. The 'primary' keyword dynamically adjusts the priority to ensure the switch retains its root status, accounting for changes in the network where other switches might also have low priorities.
there is the same question earlier this one, but taht answer is D ...
Indeed, a bit confusing, or I'm missing something
The last qsn i came across was exactly the same and it says the keyword "root" should be used because there might be 2 switches with the priority of 0 on that same network
True...am Confused
B is correct because the lowest bridge priority is the root
You can have two switches with 0 priority, but specifying one to be the root, will establish it as the root, and walk over priority number.
set as Primary dose not grantee the root stay as root always. set as zero grantees the root will always be root.
@sasquat raised a good point if two are set at pri 0 what is going to happen ?
Answer is C. From Cisco Press book 31 Days Before Your CCNA Exam: "The network administrator wants to ensure that S1 is always the root bridge (...). The following commands achieve this objective: S1(config)# spanning-tree vlan 1 root primary The 'primary' keyword automatically sets the priority to 24576 or to the next 4096 increment value below the lowest bridge priority detected on the network." This suggests to me whenever a new root bridge election is held, SW1 will update its priority so as to be the lowest.
About root primary command: https://community.cisco.com/t5/switching/spanning-tree-vlan-root-primary/td-p/1269595 Paraphrasing from this source: The "spanning-tree root primary" command is actually a macro and it is executed only one time. If after this somebody configures another device with a lower priority, this node cannot react to this and it will lose its root bridge role. If you use "spanning-tree vlan 1 priority 0", only another device with pri 0 and a lower MAC address can take the role of root bridge.
The key phrase "guaranteed is always". using the primary command causes the switch to check the existing root switch priority and then lower its priority by 4096. This is only done once thus if a new switch is introduced later with an even lower priority that switch will become root bridge. The only way to guarantee a switch remains root is to set its priority to 0.
While you are correct, if another switch with a lower mac AND a priority of 0 is added to the network, it would then become the root bridge. I agree that B is the best answer here, but technically there is no way to "guarantee" 100%.
In Rapid PVST+ (Per-VLAN Spanning Tree Plus) protocol, you can use the "spanning-tree vlan 200 root primary" command to ensure that a switch becomes the root bridge for VLAN 200. This command sets the priority of the switch to the lowest value (0) for the specified VLAN, making it the root bridge. By setting the priority to the lowest value, the switch will have the highest priority and will become the root bridge for the specified VLAN. Keep in mind that this command only affects VLAN 200 and does not impact the spanning tree topology for other VLANs. Here's the complete command: Copy switch(config)# spanning-tree vlan 200 root primary Make sure to execute this command on the desired switch to ensure it becomes the root bridge for VLAN 200 in Rapid PVST+ topology.
last question i came across with setting the priority to zero(0) was incorrect and now its correct lol... i think we need to follow our books more in as much as we need to revise
C. spanning-tree vlan 200 root primary
The spanning-tree vlan vlan_ID root command fails if the value required to be the root bridge is less than 1. https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/layer2/503_n1_1/Cisco_n5k_layer2_config_gd_rel_503_N1_1_chapter9.html#task_1163819
Correct Answer C technically B is relevant only if you want to change the priority of the root bridge, but to ensure the switch is always the root bridge you must explicitly configure it as the root eg SW4(config)#spanning-tree vlan 1 ? priority Set the bridge priority for the spanning tree root Configure switch as root <cr> https://www.omnisecu.com/cisco-certified-network-associate-ccna/how-to-configure-spanning-tree-protocol-root-primary-and-root-secondary.php
Execute the command "spanning-tree vlan 1 root primary" on a switch and then check the running config. All it lists is a priority 4096 lower than the lowest priority detected on the network. The primary/secondary commands don't do what you think they do.
thank you is there a new qoustions about ccna 2021 after changing exam rules
B true
The primary keyword sets the priority to 24,576, and the secondary keyword sets the priority to 28,672. spanning-tree vlan vlan-id root {primary | secondary} [diameter diameter]: This command executes a script that modifies certain values. Explanation in this link. https://www.ciscopress.com/articles/article.asp?p=2995351&seqNum=2
I think C is correct. When you connect another switch with the same priority 0, won't a root bridge election take place? And since an election happens, there's no guarantee that the switch will be the root since the other switch may have a lower MAC address.
The spanning-tree vlan vlan_ID root command fails if the value required to be the root bridge is less than 1. https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/layer2/503_n1_1/Cisco_n5k_layer2_config_gd_rel_503_N1_1_chapter9.html
B is correct!
I looked at other resouces because I though the answer was C, but B seems to be correct