23道新题中关于2层交换机的一道题是不是有错？

xelnara

QUESTION 13

Whichthree statements accurately describe layer 2 Ethernet switches?(choose three)

A.Microsegmentation decreases the number of collisions on the network.

B.if a switch receives a frame for an unkown destination,it uses ARP to resolvethe address.

C.Spanning Tree Protocol allows switches to automatically share vlan information.

D.In a properly functioning network with redundant switched paths,each swichedaegment will contain one

rootbridge with all its ports in the forwarding state.All other switches in thatbroadcast domain will have

onlyone root port.

E.Establishing vlans increases the number of broadcast domains.

F.Switches that are configured with vlans make forwarding decisions based on bothlayer 2 and layer 3

addressinformation.

Answer: ADF

这是我自己的分析：

哪3个选项准确的描述了2层以太网交换机？

A、微分割减少冲突域的数量。错误，微分割一般用来描述vlan微分割广播域，冲突域不变

B、如果交换机收到一个未知目标地址的帧，它会使用ARP来解析。错误，ARP工作在3层。

C、STP允许交换机之间自动共享vlan信息。错误，应该是VTP。

D、在一个工作正常的交换网络中会有一个根交换机，其他所有交换机都只有一个跟接口。正确。

E、建立VLAN增加了广播域的数量。正确。

F、配置有vlan的交换机依据2层和3层信息来做转发决定。错误，2层交换机不会处理3层信息。

题库答案明显错误，但是我自己看也觉得只有DE正确啊，往高手解答！

xelnara

还有这个题：

QUESTION 19
Which two of these are characteristics of the 802.1Q protocol?(choose two)
A. it is a layer 2 messaging protocol which maintains vlan configurations across network.
B. it includes an 8-bit field which specifies the priority of a frame.
C. it is used exclusively for tagging vlan frames and dose not address network reconvergence following switched network topology changes.
D. it modifies the 802.3 frame header,and thus requires that the FCS be recomputed.
E. it is a trunking protocol capable of carring untagged frames.
Answer: DE
Reason：个人认为应该是CE

xelnara

QUESTION 4
Which command helps a network administrator to manage memory by displaying flash memory and
NVRAM utilization?
A. show secure
B. show file systems
C. show flash
D. show version
Answer: B
我个人认为答案应该是D

wgzmk

arp（mac地址解析协议具体百度一下）是交换机专有啊，2层。D好像复杂网络如交换机多个接口都连接就不可以了。
ABE，a知道意思就可以了，其他没合适的

xelnara

回复 wgzmk 的帖子

A不明所以，
B应该不对啊，如果交换机收到一个未知目的地址的帧，它应该是泛洪到同vlan的除接收端口外所有接口才对啊。
D描述也没错啊。

wgzmk

回复 xelnara 的帖子

Which two of these are characteristics of the 802.1Q protocol?(choose two)
这题选：ＤＥ，版主的回复。C..exclusively是私有的意思应该说的isl思科的所有。

wgzmk

答案
http://blog.163.com/red_maple/blog/static/11015272006613356550/

问题Which command helps a network administrator to manage memory by displaying flash memory and  NVRAM utilization?

huj427

同问下高人

求详细解答

挑灯看剑

wzkiron

13题:
ADE
A选项,collision少了domain,不明
F错了,2层交换机只根据二层帧头转发.
19题:
DE
C是错的,exclusively是唯一的意思,不止802.1q,思科的ISL也是
4题:
看红头发的视频先的是show version
我用PT实验过 show file system在路由器上用可以显示flash和nvram的信息,在交换机上没这和命令