There are 3 modes the VTP protocol can operate on any switch throughout the network: 1)VTP server mode-By default all switches are configured as VTP Servers when first powered on. All VLAN information such as VLAN number and VLAN name is stored locally, on a separate NVRAM from where the 'startup-config' is stored. This happens only when the switch is in VTP Server mode. For small networks with a limited number of switches and VLANs, storing all VLAN information on every switch is usually not a problem, but as the network expands and VLANs increase in number, it becomes a problem and a decision must be made to select a few powerful switches as the VTP Servers while configuring all other switches to VTP Client mode. 2)VTP client mode-n Client Mode, a switch will accept and store in its RAM all VLAN information received from the VTP Server, however, this information is also saved in NVRAM, so if the switch is powered off, it won't loose its VLAN information. The VTP Client behaves like a VTP Server, but you are unable to create, modify or delete VLAN's on it. In most networks, the clients connect directly to the VTP Server as shown in our previous diagram. If, for any reason, two clients are cascaded together, then the information will propagate downwards via the available Trunk links, ensuring it reaches all switches: 3)VTP transparent mode-The VTP Transparent mode is something between a VTP Server and a VTP Client but does not participate in the VTP Domain. In Transparent mode, you are able to create, modify and delete VLANs on the local switch, without affecting any other switches regardless of the mode they might be in. Most importantly, if the transparently configured switch receives an advertisement containing VLAN information, it will ignore it but at the same time forward it out its trunk ports to any other switches it might be connected to. All switches configured to operate in Transparent mode save their configuration in their NVRAM (just like all the previous two modes) but not to advertise any VLAN information of its own, even though it will happily forward any VTP information received from the rest of the network.