i am learning the Root Priority as 32768 .How is it possible

[bibinbahuleyan263]

So my scenario is as attached

     Not switch C is root bridge for a vlan 31 .

 but the strange Thing is Switch A learns Priority as 32768.I need to understand why it hasent added vlan 031 to it .

Real outputs from switch a below

SWITCH A

========================

VLAN0031
Spanning tree enabled protocol rstp
Root ID Priority 32768
Address 0000.bc69.0580
Cost 4
Port 50 (GigabitEthernet0/2)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32799 (priority 32768 sys-id-ext 31)
Address 108c.cf52.ef80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

[Dennis Mink]

does it do that for all vlans?

also have you configured:

spanning-tree extend system-id

[bibinbahuleyan263]

Only Vlan 31 is on that switch no other Vlans .

 spanning-tree extend system-id is on by default i believe on all switches .the thing is i do not have access to that switch and thats where everything is going wrong.Its a third party manged switch .So i need some expert help by just commands if i can identify the issue.