11. Refer to the exhibit. In the diagram, the switches are running IEEE 802.1w RSPT. On which ports should root guard be enabled in order to facilitate deterministic root bridge election under normal and failure scenarios?
没有接口处于阻断状态
E. There is not enough information to determine which ports are in the blocking state.
如图所示，在这个图中，所有交换机运行IEEE802.1 RSPT协议，哪些端口是后备端口，以 便在根端口和制定端口故障后使用。
A. GE-3/1, GE-3/2 B. FE-2/1, FE-3/2 C. GE-1/1, GE-1/2 D. GE-4/1, GE-4/2 E. GE-2/1, GE-2/2 F. GE-3/1, GE-3/2, GE-4/1, GE-4/2, FE-2/1, FE-3/2
Answer: F
12. Loop guard and UniDirectional Link Detection both protect against Layer 2 STP loops. In which two ways does loop guard differ from UDLD in loop detection and prevention? (Choose two.)
环路检测和单向链路检测，保证2层STP没有环路。这两种做法不同于UDLD中的环路检测 吗?
A. Loop guard can be used with root guard simultaneously on the same port on the same VLAN while UDLD cannot. B. UDLD protects against STP failures caused by cabling problems that create one-way links.
UDLD 是为了防止电缆故障，造成一个单向故障
C. Loop guard detects and protects against duplicate packets being received and transmitted on different ports. D. UDLD protects against unidirectional cabling problems on copper and fiber media. E. Loop guard protects against STP failures caused by problems that result in the loss of BPDUs from a designated switch port.
环路检测保护是在BPDU信息在制定端口失效的故障
Answer: BE
13. Which standard supports multiple instances of spanning tree?
那个标准协议支持多实例生成树
A. 802.1D B. 802.1s C. 802.1w D. 802.1z
Answer: B
14. Spanning Tree Protocol calculates path cost based on which of these?
生成树中的计算成本值和哪个参数有关
A. interface bandwidth B. interface delay C. interface bandwidth and delay D. hop count E. bridge priority
Answer: A
15. Refer to the exhibit. What type of issue does this error log indicate if the IP address in the error log is located off of the Router A WAN?
如图所示，什么类型的问题，这个错误的日志指出 如果有ip 地址错误的日志，就关闭路由 器A的外网接口
A. HSRP standby configuration error B. HSRP burned-in address error C. HSRP secondary address configuration error D. this is not an HSRP problem, but rather an STP error or router or switch configuration issue
这不是一个HSRP的问题，但是相反的线路的问题或一个路由器或一个交换机的配置问题
Answer: D
16. What two features in Cisco switches help prevent Layer 2 loops? (Choose two.)
那两个是CISCO交换机的2层防环的功能 A. UniDirectional Link Detection单向链路检测
B. Hot Standby Router Protocol C. Virtual Router Redundancy Protocol D. PortFast E. root guard F. loop guard环路保护
Answer: AF
17. Refer to the exhibit. Which switching feature is being tested?
如图所示，正在测试哪种交换功能?
A. loop guard B. PortFast C. root guard
环路保护
D. BDPU guard
Answer: A
18. In Layer 2 topologies, spanning-tree failures can cause loops in the network. These unblocked loops can cause network failures because of excessive traffic. Which two Catalyst 6500 features can be used to limit excessive traffic during spanning-tree loop conditions? (Choose two.)
在2层的拓扑中，生成树发生故障会导致网络的环路。成环的网络中的流量可以导致网络的 瘫痪。在6500交换机中哪两个功能可以防止生成树的环路过高的流量
A. loop guard
B. storm control
风暴控制 广播抑制
C. storm suppression
D. broadcast suppression
E. BPDU guard
Answer: BD
19. Why does RSTP have a better convergence time than 802.1D?
为什么快速生成树协议收敛时间比802.1d的收敛时间更短
A. it is newer B. it has smaller timers C. it has less overhead D. it is not timer-based
Answer: D
20. Under which two circumstances would an RSTP bridge flush its CAM table? (Choose two.) 在哪两种情况下RSTP桥会刷新MAC地址表 A. upon a port state change
B. upon receiving a topology change notification接到拓扑发生改变的通知
C. when transitioning from discarding to forwarding从丢弃状态过度到转发状态时D. when transitioning from forwarding to discarding E. only when changing from listening to discarding F. when CAM resources have been completely used up
Answer: BC