Refer to the exhibit. Which two commands ensure that DSW1 becomes root bridge for VLAN 10? (Choose two)

Question

Exhibits

Options

• ADSW1(config)#spanning-tree vlan 10 priority 4096
• BDSW1(config)#spanning-tree vlan 10 priority root
• CDSW2(config)#spanning-tree vlan 10 priority 61440
• DDSW1(config)#spanning-tree vlan 10 port-priority 0
• EDSW2(config)#spanning-tree vlan 20 priority 0

• A
  86% (18)
• B
  10% (2)
• E
  5% (1)

Explanation

Explanation

To make DSW1 the root bridge for VLAN 10, its bridge priority must be lower than all other switches. Option A is correct because setting DSW1's VLAN 10 priority to 4096 (a valid multiple of 4096, lower than the default of 32768) makes it the most preferred root. Option C is correct because setting DSW2's VLAN 10 priority to 61440 (the highest possible value) makes DSW2 the least preferred, reinforcing DSW1 as root - both commands work together to guarantee the outcome.

Why the distractors are wrong:

• B is incorrect because priority root is not valid syntax - the correct command is spanning-tree vlan 10 root primary
• D is incorrect because port-priority affects which port is chosen in a topology, not which switch becomes root bridge
• E is incorrect because it modifies VLAN 20, not VLAN 10, so it has no effect on root bridge election for VLAN 10

Memory Tip

Think "Lower wins, Higher loses" - to guarantee root bridge status, lower the priority on the switch you want as root, and raise the priority on switches you don't want as root. Valid priorities are always multiples of 4096 (0, 4096, 8192...61440).

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