An engineer plans to connect three switches (sw1, sw2, and sw3) in a lab. before connecting the switches, he starts by configuring all three switches as vtp servers, with matching ctp domain name and password. he then configures some vlans on each switch so that switch sw3 has a revision number of 10, switch sw2 has a revision number of 6, and switch sw1 has a revision number of 8. only then does he engineer connect the switches with trunks: first sw1 to sw2, then sw2 to sw3, and then sw3 to sw1. switch sw1 is elected the stp root switch in vlan 1. which answer most accurately states which vlan configuration database is used, and why?