What happens to the revision number in a VTP server when a VLAN is added, modified, or deleted?

When a VLAN is added, modified, or deleted in a VTP server, the revision number increases. The revision number acts as a version control mechanism within the VLAN Trunking Protocol (VTP), allowing VLAN information to be tracked and synchronized across all switches in the VTP domain.

Each time a significant change is made—such as the addition, modification, or deletion of a VLAN—the VTP server increments the revision number. This incrementing process is essential because it communicates to other VTP devices that there has been a change in the VLAN configuration, and they may need to update their own VLAN databases accordingly.

If a switch receives a VTP advertisement with a higher revision number than it currently has, it will replace its local VLAN information with the new data, ensuring consistency within the VTP domain. This system of revising numbers ensures that all switches operate with the most current VLAN information and helps to maintain network integrity.