Configuring Switch as Root for VLAN 750

C.

The correct answer is A. Switch(config)#spanning-tree vlan 750 priority 38418607.

Explanation: The Spanning Tree Protocol (STP) is a protocol that prevents loops in a network by creating a loop-free logical topology. In STP, one switch is elected as the root bridge for the network. All other switches in the network use the root bridge as a reference point to calculate the shortest path to the root bridge.

To ensure that the switch is always the root for VLAN 750, we need to configure the switch to have the lowest priority value for VLAN 750. The priority value ranges from 0 to 65535, where a lower value indicates a higher priority.

Option A, Switch(config)#spanning-tree vlan 750 priority 38418607, sets the priority value for VLAN 750 to 38418607, which is the lowest possible priority value for VLAN 750. This configuration ensures that the switch is always the root for VLAN 750.

Option B, Switch(config)#spanning-tree vlan 750 priority 0, sets the priority value for VLAN 750 to the lowest possible value across all VLANs, which may not be desirable if the switch needs to be the root for only a specific VLAN.

Option C, Switch(config)#spanning-tree vlan 750 root primary, forces the switch to become the root bridge for VLAN 750, but if a more preferred root bridge is added to the network, the switch may lose its position as the root bridge.

Option D, Switch(config)#spanning-tree vlan 750 priority 614440, sets the priority value for VLAN 750 to a higher value, which may cause another switch with a lower priority value to become the root bridge for VLAN 750.