41. Network A has a spanning-tree problem in which the traffic is selecting a longer path. How is the path cost calculated?
网络A 的生成树，其中一条很长的路径，他的成本怎么计算?
A. number of hops B. priority of the bridge C. interface bandwidth D. interface delay E. None of the above
Answer: C
42. You deployed new fibers in your networkto replace copper spans that were too long. While reconnecting the network, you experienced network problems because you reconnected wrong fibers to wrong ports. What could you do to prevent this type of problem in the future, particularly when connecting and reconnecting fiber pairs?
你正在部署你的网络拥光纤来替代过长的铜线路， 在从新联网时你遇到了问题。 因为你错误 的链接了发送接收端口， 你可以做什么来防止以后在发生这样的事情， 特别是在链接一对光 纤的时候
A. Only use fiber in pairs.
B. Configure root guard on your switches.
C. Do not use fiber but use copper.
D. Configure UDLD to prevent one-way link conditions.
配置UDLD来防止单向链路的问题。
Answer: D
43. While deploying a new switch, you accidently connect ports 3/12 and 3/18 together, creating a loop. STP detected it and placed port 3/18 in blocking mode. Why did STP not place port 3/12 in blocking mode instead?
当部署一个新的交换机，你无意的链接了3/12/和3/18，形成了一个环路，STP把3/18端口 设置为阻断端口，为什么没有把3/12设置为阻断端口呢?
A. Port 3/12 was already up and forwarding before the loop was created.
B. Port priority is based on lowest priority and lowest port number. 因为端口ID 3/12比较低
C. You connected the wire on port 3/18 last.
D. None of the above, it is purely random.
Answer: B
44. Two routers configured to run BGP have been connected to a firewall, one on the inside interface and one on the outside interface. BGP has been configured so the two routers should peer, including the correct BGP session endpoint addresses and the correct BGP session hop-count limit (EBGP multihop). What is a good first test to see if BGP will work across the firewall?
有两个运行BGP的路由器连接到防火墙， 一个在inside接口， 一个在outside 接口。 BGP 已经配置并且已经成为了邻居，包含正确的配置了BGP网络地址和正确的BGP跳数的限制 (EBGP的多跳设置)，怎么能够最好的测试BGP工作在防火墙上。
A. Attempt to TELNET from the router connected to the inside of the firewall to the router connected to the outside of the firewall. If telnet works, BGP will work, since telnet and BGP
both use TCP to transport data.
用在inside接口上的路由器telnet 到在outside 接口上的路由器。如果telnet 正常工作侧说明 BGP能正常工作，因为telnet 和BGP 都是使用TCP 来传输数据的
B. Ping from the router connected to the inside interface of the firewall to the router connected to the outside interface of the firewall. If you can ping between them, BGP should work, since BGP uses IP to transport packets.
C. There is no way to make BGP work across a firewall without special configuration, so there is no simple test that will show you if BGP will work or not, other than trying to start the peering session. D. There is no way to make BGP work across a firewall.
Answer: A
45. Refer to the exhibit. In this network, R1 has been configured to advertise a summary route, 192.168.0.0/22, to R2. R2 has been configured to advertise a summary route, 192.168.0.0/21, to R1. Both routers have been configured to remove the discard route (the route to null created when a summary route is configured) by setting the administrative distance of the discard route to 255.
如图所示，在这个网络中，R1通告了192.168.0.0/22的汇总路由给R2， R2通告了192.168.0.0/21的汇总路由给R1。两台路由器都配置了汇总路 由的null0 接口来防止路由的环路。发生什么情况，R1能收到一个去192.16 8.3.1的数据包?
What will happen if R1 receives a packet destined to 192.168.3.1?
A. The packet will loop between R1 and R2. 这个包在R1和R2之间形成了环路
B. It is not possible to set the administrative distance on a summary to 255.
C. The packet will be forwarded to R2, where it will be routed to null0.
D. The packet will be dropped by R1, since there is no route to 192.168.3.1.
Answer: A
46. Refer to the exhibit. In this network, R1 is configured not to perform autosummarization within EIGRP. What routes will R3 learn from R2 through EIGRP?
如图所示，在这个网络中 R1配置为在EIGRP中不做自动汇总，那么R3能从R2学到什么 EIGRP的路由信息。
A. 172.30.1.0/24 and 10.1.2.0/24; EIGRP only performs autosummarization at the edgebetween two major networks.
172.30.1.0/24 和 10.1.2.0/24 EIGRP在两个较大的网络边缘只能执行自动汇总。
B. 172.30.0.0/16 and 10.1.2.0/24; R2 will perform autosummarization, although R1 will not.
C. Since R2 is configured without autosummarization, it will not propagate the 172.30.1.0/24 route. D. 172.30.0.0/8 and 10.0.0.0/8.
Answer: A
47. Which types of prefixes will a router running BGP most likely advertise to an IBGP peer, assuming it is not configured as a route reflector?
那种类型的前缀，在一个路由器运行BGP上最有可能通告给你一IBGP邻居，假设他没有配 置为一个路由反射器
A. prefixes received from any other BGP peer and prefixes locally originated via network statements or redistributed
从EBGP邻居收到前缀声明和前缀声明来自这个网络或重发布进来的。
B. all prefixes in its routing table
C. prefixes received from EBGP peers and prefixes locally originated via network statements or redistributed
D. prefixes received from EBGP peers and prefixes received from route reflectors
E. prefixes received from other IBGP peers, prefixes received from EBGP peers, and prefixes redistributed to BGP
F. prefixes received from other IBGP peers and prefixes received from route reflectors www.Examw.com
Answer: C
48. You have two EBGP peers connected via two parallel serial lines. What should you do to be able to load-balance between two EBGP speakers over the parallel serial lines in both directions?
你在两条串行线路上有两个EBGP邻居，怎么做来实现在两个EBGP邻居间的负载均衡
A. nothing, BGP automatically load-balances the traffic between different autonomous systems on all available links
B. peer between the eBGP speaker's loopbacks, configuring eBGP multihop as required, and use an IGP to load-share between the two equal-cost paths between the loopback addresses
用loopback接口建立EBGP邻居，必须配置BGP的多跳。在IGP中写入两个成本相同的到 EBGP邻居的Loopback口的路由
C. configure a loopback as update source for both EBGP peers and have on each AS an IGP to introduce two equal-cost paths to reach the EBGP peer loopback address; it is also necessary to use the next-hop-self command
D. use the ebgp-load-balance command on the neighbor statement on both sides E. configure a loopback as update source for both EBGP peers and have on each AS an IGP to introduce two equal-cost paths to reach the peer loopback address; it is also necessary to use the ebgp-multihop and next-hop-self commands
Answer: B
49. Which of these best identifies the types of prefixes a router running BGP will advertise to an EBGP peer?
哪一个是最能确认的前缀类型，在一个路由器和是他的EBGP邻居
A. prefixes received from any other BGP peer and prefixes locally originated via network
statements or redistributed to BGP
从一个BGP邻居收到的前缀，是本地的网络通告的或是重发布进入BGP的
B. all prefixes in its IP routing table C. only prefixes received from EBGP peers and prefixes locally originated via network statements or redistributed D. only prefixes received from EBGP peers and prefixes received from route reflectors E. all prefixes in its routing table except the prefixes received from other EBGP peers F. all prefixes in its routing table except the prefixes received from other IBGP peers
Answer: A
50. Which of these statements best describes the major difference between an IPv4-compatible tunnel and a 6to4 tunnel?
下面哪一个描述IPv4兼容通道和IPv6 to IPv4隧道的区别最好的一项
A. An IPv4-compatible tunnel is a static tunnel, but an 6to4 tunnel is a semiautomatic tunnel.
B. The deployment of a IPv4-compatible tunnel requires a special code on the edge routers, but a 6to4 tunnel does not require any special code.
C. An IPv4-compatible tunnel is typically used only between two IPv6 domains, but a 6to4 tunnel is used to connect to connect two or more IPv6 domains.
一个IPv4兼容的隧道通常只用两个IPv6的域，但一个6to4隧道是用来连接两个或多个连接 的IPv6域
D. For an IPv4-compatible tunnel, the ISP assigns only IPv4 addresses for each domain, but for a 6to4 tunnel, the ISP assigns only IPv6 addresses for each domain.
Answer: C