TP should not be used. A good example of a network that should not use VTP is an ecommerce website. Changes to the VLAN design should occur rarely, if ever, SO there is little benefit to deploying VTP. Chapter 6: VLAN Trunking Protocol In larger, more dynamic environments where VTP is of use, you must follow proper procedures to ensure that unintended problems do not occur. In the preceding example, security measures such as enabling VTP passwords (discussed in the next section) would probably have prevented the disaster. More importantly, perhaps, connecting rogue switches to a production network should not be allowed without change-control procedures being followed. A good way to prevent the connection of rogue switches is to shut down all switch ports that are not in use. This policy forces people to request that ports be turned up when they want to connect devices to a switch. Configuring VTP To use VTP, you must configure a VTP domain. You'll also need to know how to set the mode on your switches. Further configuration options include setting VTP pass- words and configuring VTP pruning. VTP Domains The default VTP domain is null. Bear this in mind when implementing VTP, because trunks negotiated using the null VTP domain will break if you assign a different domain to one side. This behavior differs from switch to switch. For example, the Catalyst 5000 will not negotiate trunks unless a VTP domain has been set for each switch. On some switches, such as the Cisco 6500, the null domain will be overwritten if a VTP advertisement is received over a trunk link, and the switch will inherit the VTP domain from the advertisement. If a VTP domain has been previously configured, this will not occur. Also, once you've changed a switch's VTP domain to something other than null, there is no way to change it back to null short of erasing the configuration and rebooting. Set or change the VTP domain in IOS with the vtp domain command: 3750-IOS (config)#vt domain GAD-Lab Changing VTP domain name from NULL to GAD-Lab 2wod: %D