Cisco CCNA mock exam questions sample test – Question 211

Which of the following statements are NOT true, based on the output below?
211q

A. This switch is the root bridge.
B. This switch has a priority of 32778.
C. This switch has a MAC address of 0015.63f6.b700.
D. All ports will be in a state of discarding, learning, or forwarding.
E. All designated ports are in a forwarding state.
F. This switch is using the default priority for STP


Correct Answer: AC

Explanation:
The upper half of the output provides information about the root bridge. It indicates that the root bridge has a bridge priority of 24586 and a MAC address of 0015.63f6.b700. The bottom half of the output pertains to the current switch, and indicates that this switch has a bridge priority of 32778 and a MAC address of 000f.f794.3d00.
The value of the switch bridge priority is arrived at by adding the configured priority of 32768, which is indicated by the line priority 32768 sys-id-ext 10, to the VLAN ID of 10. Because 32768 is the default bridge priority for STP, this switch is set to the default priority for STP.
The priority of this switch is 32778. The bridge priority is arrived at by adding the configured priority of 32768 to the VLAN ID of 10.
This switch is not the root bridge, as indicated by the differences in priorities and MAC addresses between the root ID and the bridge ID output. If this were the root bridge, the MAC addresses and priority values would be the same in both the Root ID and the Bridge ID sections.
Finally, when a switch is using RSTP, as indicated by the output Spanning tree enabled protocol rstp, all ports will be in a state of discarding, learning, or forwarding, with all designated ports in a forwarding state. When RSTP has converged, all ports will be in either the discarding or forwarding states.

Objective:
LAN Switching Fundamentals
Sub-Objective:
Configure, verify, and troubleshoot STP protocols
References:
Cisco > Cisco IOS Bridging Command Reference > show spanning-tree