1．which of the following is true regarding the use of switches and hubs for network connectivity?
A. Switches take less time to process frames than hubs take.
B. Switches do not forward broadcasts.
C. Hubs can filter frames.
D. Using hubs can increase the amount of bandwidth available to hosts.
E. Switches increase the number of collision domains in the network.
Answer: E
解释一下：Switch是一个二层的设备，而hub是一个一层的设备。switch可以基于MAC地址对流量进行控制，但hub不行，他对于接收到的帧都是无条件地从所有接口转发出去的。switch和 hub都不能过滤组播和广播的流量，对于这些流量他们都是无条件的转发。
而hub的所有端口在同一个冲突域和广播域中，但switch的是在同一个VLAN中的端口在相同的广播域中，每个端口是一个冲突域。所以说switch与hub相比是增加了网络中冲突域的数量。
2．Why has the network shown in the exhibit failed to converge?
A. The no auto-summary command needs to be applied to the routers.
B. The network numbers have not been properly configured on the routers.
C. The subnet masks for the network numbers have not been properly configured.
D. The autonomous system number has not been properly configured.
E. The bandwidth values have not been properly configured on the serial interfaces.
Answer: A
解释一下：EIGRP在网络的边界也是会进行自动汇总的。而我们所说的网络边界指的是同一台路由器的两个端口的主网络号不相同，那么这台路由器我们就说他是在一个网络的边界，他会自动汇总到他们的主网络。
因此上图中的New York 和 Sydney都是边界路由器，他们会将他们接口的地址汇总到192.168.20.0/24和10.0.0.0/8发送出去。由于水平分割的原则，他们是不会接收对端发过来的网段的。如果是关闭了自动汇总，那么EIGRP是会将明细的路由发送出去的，那么水平分割也是不会阻断他们的。
3．What are two recommended ways of protecting network device configuration files from outside network security threats? (Choose two.)
A. Allow unrestricted access to the console or VTY ports.
B. Use a firewall to restrict access from the outside to the network devices.
C. Always use Telnet to access the device command line because its data is automatically encrypted.
D. Use SSH or another encrypted and authenticated transport to access device configurations.
E. Prevent the loss of passwords by disabling password encryption.
Answer: BD
解释一下：为了保护从外部访问内部的安全性。可以使用一个防火墙来限制外部访问内部的设备，也可以通过SSH或其他加密的传输去访问内部的设备。
4．What are two characteristics of Telnet? (Choose two.)
A. It sends data in clear text format.
B. It is no longer supported on Cisco network devices.
C. It is more secure than SSH.
D. It requires an enterprise license in order to be implemented.
E. It requires that the destination device be configured to support Telnet connections.
Answer: AE
解释一下：关于telnet的特性。telnet发送数据都一以明文的形式发送的。安全性没有SSH好，因为telnet是基于应用层的应用，因此他需要对端的设备也支持telnet的连接。
5．Refer to the exhibit. Why does RouterA show multiple unequal cost paths to network 192.168.81.0/24?
A. A variance was configured for EIGRP autonomous system 109.
B. The EIGRP topology table displays all routes to a destination.
C. The EIGRP topology table shows only backup routes to a destination.
D. Multiple floating static routes were configured to network 192.168.81.0 via interface Serial0.
Answer: B
解释一下：show ip eigrp topology显示的是EIGRP的拓扑表。在这显示这台路由器所能到达所有目的地的所有可以走的路径，然后根据比较metric来选出最优的路径来放到路由表中。
[ 本帖最后由 bengyaju 于 2007-12-8 21:02 编辑 ] | 
发表于 2007-12-7 17:09
| 
发表于 2007-12-7 22:22
| 
难的能抢到板凳
