stp root switch...

from cisco's 3560/3750 guide which of course you can download...

If all switches in a network are enabled with default spanning-tree settings, (and when they come out of the box they are wearing their birthday suits) the switch with the lowest MAC address becomes the root switch.


that is gospel...

priority is default at 32768...

that is gospel...

this is the BID of this switch on vlan 10...

dsw1#sh spann                                                                 
                                                                              
VLAN0010                                                                      
  Spanning tree enabled protocol rstp                                         
  Root ID    Priority    32778        

32768 + 10 is 32778...

the priority can change all that ONLY if it has been configured to do so... and if it has been configured to do so, the mac doesn't matter...

again, that is if it has been configured to do so...

which means the priority is an afterthought, although we all know you want to be deterministic about the placement of the root switch...

out of the box, MAC is king...

your witness, counselor...