CCNA640-802题库解析–VLAN的定义以及应用

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本文主要结合例题讲解VLAN的定义与作用，以及应用方面。
A company is installing IP phones. The phones and office computers connect to the same device. To ensure maximum throughput for the phone data, the company needs to make sure that the phone traffic is on a differentnetworkfrom that of the office computer data traffic. What is the best network device to which to directly connect the phones and computers, and what technology should be implemented on this device? (Choose two.)
A:hub
B:router
C:switch
D:STP
E:subinterfaces
F:VLAN
Correct Answers:C, F
公司的语音设备和办公的设备都连在相同的设备上，还要确保语音的数据流在不同与公司的办公的数据流量，可以通过在交换机上配置VLAN的方法来区分两种不同的数据流。
知识点扩展：虚拟局域网(VLAN)，是指网络中的站点不拘泥于所处的物理位置，而可以根据需要灵活地加入不同的逻辑子网中的一种网络技术。可以用来控制广播风暴，提高网络安全性，而且使复杂的网络管理起来更简便。看后面的例题会很容易理解。
Refer to the exhibit. The network manager is evaluating the efficiency of the current network design.RIPv2is enabled on all Layer 3 devices in the network. What network devices participate in passing traffic from the PC at 10.10.1.7 to File Server at 10.20.1.6 in the order that they will forward traffic from source to destination?
A: Switch1, Switch2
B: Switch1, Switch2, Router2, Switch2
C:Switch1, Router1, Switch1, Switch2
D: Switch1, Router1, Router2, Switch2
Correct Answers:D
PC机和File Server属于不同的VLAN，因为一个VLAN就是一个广播域，不同VLAN间的通信需要通过trunk和三层路由的帮助，在交换机和路由器之间封装TRUNK，这样可以允许交换机间的二层的通讯，但是由于两个VLAN是划分到不同的网段中的，因此需要借助路由器的路由功能来实现三层的可达，可以将VLAN中的主机的网关指定为路由器与该VLAN相连的子接口的地址，这样VLAN中的数据包就都会发往网关，而由网关来进行进一步的转发。
Refer to the exhibit. The FMJ manufacturing company is concerned about unauthorized access to the Payroll Server. The Accounting1, CEO, Mgr1, and Mgr2 workstations should be the only computers with access to the Payroll Server. What two technologies should be implemented to help prevent unauthorized access to the server? (Choose two.)
A:access lists
B:encrypted router passwords
C:STP
D:VLANs
E:VTP
F:wireless LANs
Correct Answers:A, D
需要控制只允许哪些组可以访问服务器，组中的哪些用户可以访问，使用的技术当然有ACL和VLAN了。实现针对不同的部门划分VLAN，然后按各部门需求应用访问列表就可以实现。
Refer to the exhibit. How many broadcast domains exist in the exhibited topology?
A: one
B: two
C: three
D: four
E: five
F: six
Correct Answers:C
这是一个关于广播域的问题，在默认的情况下，交换机是共享广播域的，VLAN就是将广播限制在一个更小的范围，抑制其广播风暴。一个VLAN就是一个广播域，一个VLAN中的广播的流量是不能传到其他的区域的，我们看上图三个VLAN就是三个广播域了。
What is the function of the command switchport trunk nativevlan999 on aCiscoCatalyst switch?
A: It creates aVLAN999 interface.
B: It designatesVLAN999 for untagged traffic.
C: It blocksVLAN999 traffic from passing on the trunk.
D: It designatesVLAN999 as the default for all unknown tagged traffic.
Correct Answers:B
在TRUNK上NativeVLAN的数据是无标记的(Untagged),是指如果TRUNK失败的时候端口上仍然能正常工作的VLAN，在这指定在NativeVLAN为999，表明VLAN999为不用打标签的VLAN。
Which two statements describe theCiscoimplementation of VLANs? (Choose two.)
A:VLAN1 is the default EthernetVLAN.
B:CDP advertisements are only sent onVLAN1002.
C:By default, the switch IP address is inVLAN1005.
D:VLANs 1002 through 1005 are automatically created and cannot be deleted.
Correct Answers:A, D
VLAN1是默认VLAN，VLAN1002-1005，这是保留的(reserved for Token Ring and FDDI VLANs),会自动创建，而且是不能删除的。
When a new trunk link is configured on anIOSbased switch, which VLANs are allowed over the link?
A: By default, all defined VLANs are allowed on the trunk.
B: Each singleVLAN, orVLANrange, must be specified with the switchport mode command.
C: Each singleVLAN, orVLANrange, must be specified with thevtpdomain command.
D: Each singleVLAN, orVLANrange, must be specified with thevlandatabase command.
Correct Answers:A