CCNP Practice Question: Spanning-tree vlan 10 priority 4096 What is the…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  The switch will have a bridge priority of 4096 for VLAN 10, increasing its chance to become root bridge.

  Why this is correct

  The command 'spanning tree vlan 10 priority 4096' sets the bridge priority for the VLAN 10 spanning tree instance to 4096, lowering it from the default 32768. Because STP elects the root bridge using the lowest bridge ID (priority + MAC address), this significantly increases the switch's chances of winning the election for that VLAN. However, it does not guarantee the switch becomes root—any switch with a lower priority value or an equal priority but lower MAC address will still be preferred.

• ✗

  The switch will have a bridge priority of 4096 for all VLANs.

  Why it's wrong here

  In Rapid PVST+ or PVST+, every VLAN runs an independent spanning tree instance, and the bridge priority is configured per VLAN. The command syntax 'spanning tree vlan 10 priority 4096' explicitly targets only VLAN 10; it does not alter the priority for other VLANs. Therefore, saying the switch will have priority 4096 for all VLANs is incorrect—other VLANs retain their current (normally default) priority.

• ✗

  The switch will become the root bridge for VLAN 10 immediately.

  Why it's wrong here

  Setting bridge priority to 4096 merely improves the switch's likelihood of becoming the root, but root election is a dynamic process based on comparing bridge IDs among all switches in the topology. If another switch has a lower priority (e.g., 0) or the same priority with a numerically lower MAC address, it will still become root for VLAN 10. Moreover, the switch does not become root instantly upon configuration; the STP election must complete and BPDUs must propagate before the root role is determined.

• ✗

  The switch will have a bridge priority of 4096 for VLAN 10 and all other VLANs will use 32768.

  Why it's wrong here

  This statement incorrectly suggests the command explicitly assigns priority 32768 to all other VLANs. In actuality, the command only changes VLAN 10's priority; other VLANs simply retain whatever priority they had prior—by default 32768, but they could have been manually configured to something else. Thus, the claim that they 'will use 32768' is not a guaranteed outcome and misrepresents the VLAN-specific nature of the command.