Source: CCIE Routing and Switching Exam Certification Guide
Even though the Catalyst switch is configured as a VTP client, and not a server, it can
erase the information of an existing network. To reset the configuration revision number on a Catalyst switch, you must either change the switch mode to transparent then back to server or client with the command
vtp mode [server | client | transparent]
in global configuration mode, or change the VTP domain name and then set it back using the command
vtp domain name
in global configuration mode.
Even though the Catalyst switch is configured as a VTP client, and not a server, it can erase the information of an existing network.
The maximum VLANs VTP can support is 1005. You can configure normal-range VLANs (2 through 1000) when the switch is in either VTP server or transparent mode. However, you can only configure extended-range VLANs (1025 through 4094) in VTP transparent switches (ie pass through).
VTP v2 is not much different than VTP V1. The major difference is that VTP V2 introduces support for Token Ring VLANs. If you use Token Ring VLANs, you must enable VTP V2. Otherwise, there is no reason to use VTP V2. Changing the VTP version from 1 to 2 will not cause a switch to reload.
In VTP version 2, if a switch is in transparent mode, it will forward the message without checking version information. A transparent switch using VTP version 1 will check the domain and version before if forwards the frame.
•Support for extended VLANs (4094).
•Support for the creation and advertising of private VLANs.
•Support for VLAN instances and MST mapping propagation instances.
•Adds a new mode called "primary server" which is the only one allowed to make changes to the domain.
•Improved server authentication. VTP version 2 stored the password as ASCII in the running config. V3 stores it a hex number.
•Protection from the "wrong" database accidentally being inserted into a VTP domain.
•Interaction with VTP version 1 and VTP version 2.
•Ability to be configured on a per-port basis.