Exam 200-301 topic 1 question 185 discussion

Although the spanning-tree vlan 750 root primary command will ensure a switch will have a bridge priority value lower than other bridges introduced to the network, the spanning-tree vlan 750 priority 0 command ensures the bridge priority takes precedence over all other priorities.

B i correct, note alwayes

-root primary command only sets the priority to 24576 -The root primary command does not override a priority of 0. -because priority 0 is lower than 24576.

root primary gives a priority of 8192 (4096x2) , STP priority goes in increments of 4096 due the the VLAN tag bits 2^12. from the 802.1q tag that we need in order to manage vlans. priority 0 is the best for STP.

From Google's Gemini : "Both options will likely make the switch the root bridge for VLAN 750 under most circumstances. Option B (priority 0) offers a more deterministic approach by setting the lowest possible priority. Option C (root primary) is simpler to configure but can be overridden by a lower bridge priority on another switch. For the CCNA exam, it's generally advisable to choose the most reliable option. Therefore, Option B (priority 0) would be the recommended answer."

For B or C which one is correct, that need to check the Cisco IOS version. Earlier Cisco IOS versions: It's possible that older versions might not have a dedicated root primary command. You might need to achieve a similar effect by setting an extremely low bridge priority for VLAN 750. However, this is not ideal as other switches with even lower priorities could still become the root bridge. Cisco IOS versions supporting Root Guard: Some Cisco IOS versions might support a feature called "Root Guard." This feature can be used on specific ports to prevent any other switch from becoming the root bridge on that port. This could be an alternative approach to influence root bridge selection for a specific VLAN. The concept of forcing a switch to be the root bridge is valid, but the exact command syntax might not be spanning-tree vlan 750 root primary in all Cisco IOS versions. It's crucial to verify the supported options for your specific environment to ensure proper configuration.

To ensure that a switch is always the root of VLAN 750 in a Spanning Tree Protocol (STP)-based Ethernet network, you can use the "priority 0" command in the specific VLAN configuration or the "primary root" command globally. - **Priority 0:** By setting the priority of VLAN 750 to 0, you are setting the switch's priority to the lowest value possible, or that makes it the strongest candidate to be the root of that VLAN. - **Primary Root:** The "primary root" command is used to force the switch to become the root of the STP tree globally across all VLANs. It has set the switch's global priority to the lowest possible value, ensuring that it is chosen as the root on all VLANs, including VLAN 750. Both configurations will achieve the goal of ensuring that the switch is always the root of VLAN 750. Choosing between them depends on your preference and your specific network configuration. If you want to ensure that only a specific VLAN is affected, use "priority 0" in the VLAN configuration. If you want the switch to be the root of all VLANs, use "primary root". B is correct

it´s B

priority 0 its the anwser

I did the test on GNS3, and the sw with the priority of 0 became the Root bridge over the sw with the root primary. Then restated the interfaces and the priority of 0 always became the root.

The answer is B because if someone configures in another switch of the network the priority 4096, in the switch that you wirte root primary shows something like this: SWPO2(config)#spanning-tree vlan 1 root primary % Failed to make the bridge root for vlan 1 % It may be possible to make the bridge root by setting the priority % for some (or all) of these instances to zero. I've recently tested it

Answer is both B or C, or neither. If the current root SW is with priority 0 and has the smallest MAC then another SW is configured with; a) root primary command -> root stays as is b) priority 0 command -> root stays as is  If the current root SW is with priority 1 or more then another SW is configured with; c) root primary command -> this SW is the new root d) priority 0 command -> this SW is the new root

B i correct, note alwayes

Can a bridge priority be set to 0???

Always priority 0 it trumps the root command

C is correct

If you enter "root primary" into the command prompt, then it is 100% assured that the switch will be the primary root. Therefore C is correct. gg good day Go Dodgers