te, the first thing it does is compare the VTP domain name in the update to its own. If the domains are different, the update is ignored. If they are the same, the switch compares the update's configuration revision number to its own. If the revision number of the update is lower than or equal to the switch's own revision number, the update is ignored. If the update has a higher revision number, the switch sends an advertisement request. The response to this request is another summary advertisement, followed by subset advertisements. Once it has received the subset ad- vertisements, the switch has all the information necessary to implement the required changes in the VLAN configuration. When a switch's VTP domain is null, if it receives a VTP advertisement over a trunk link, it will inherit the VTP domain and VLAN configura- tion from the switch on the other end of the trunk. This will happen only over manually configured trunks, as DTP negotiations cannot take place unless a VTP domain is configured. Be careful of this behavior, as it can cause serious heartache, nausea, and potential job loss if you're not (or the person before you wasn't). Switches also send advertisement requests when they are reset and when their VTP domains are changed. To answer the question posed earlier, assuming that both SW1 and SW2 started with the same configuration revision number, whichever switch submits the change first will "win," and have its change propagated throughout the domain, as it will be the first switch to advertise a higher configuration revision number. The changes made on the other switch will be lost, having effectively been overwritten. There will be no indication that these changes were lost or even made. VTP Pruning On large or congested networks, VTP can create a problem when excess traffic is sent across trunks needlessly. Take, for example, the network shown in Figure 6-3. The switches in the gray box all have ports assigned to VLAN 100, while the rest of the switches do not. With VTP active, all of the swit