In the topology above, we see DSW2 has lowest priority 24576 so it is the root bridge for VLAN 10 so surely all traffic for this VLAN must go through it. All of DSW2 ports must be in forwarding state. And: + The direct link between DSW1 and ALSW1 is blocked by STP. + The direct link between DSW1 and ALSW2 is also blocked by STP. Therefore PC1 must go via this path: PC1 -> ALSW1 -> DSW2 -> DSW1.