The network command “matches” one or more interfaces on a router. For each interface,
the network command causes the router to do three things:
1 The router broadcasts or multicasts routing updates out an interface.
2 The router listens for incoming updates on that same interface.
3 The router, when sending an update, includes the subnet of that interface in the
routing update
五.考题的疑问 一些考题的疑问 31日考试，近日看题，有些地方不明白，希望大家能帮忙解答一 下，不胜感谢 1 you need to find out the IPX address on a series router,which command displays all routed protocols and the interfaces on which the protocol is enable ? A show protocols B show interfaces 应该是A吧？B不能显示all routed protocols吧。
2 in what which mode switch read first part of frame with destination address and send frame immediately? A cut-through B fragment-free C something-else 应该是fast-forward，fragment-free 还要检查前64字节的出错，不会"immediately"转发，所以选C吧？
3. you telnets to a pc on a remote subnet,which MAC address willl be present in the ARP table when you issue the show arp command? A local router Ethernet port B destination host Ethernet port 没有用过这个命令，假如没有telnet，是不是就是local router Ethernet port啊？
4 consider Frame Relay multipoint subinterfaces.which is a valid statemant? A all the routers are required to the fukky meshed B all routers must be in the same subnet to forward routing updates and broadcasts C Multipoint is the default configration for Frame Relay subinterfaces 这题应该是B吧。我看电子教材上说的是“multipoint is used if you want the router to forward broadcasts and routing updates that it receives.select this if routing routing IP and you want all routers in same subnet”
5 which of the following are ture about 3 of the OSI model ? A it uses broadcast address B it establishes network address 我看的testking选的是A。它的解释是layer 3 does not establish addresses rather it uses the addresses to route information.可我觉得它不建立网络地址又怎么能路由呢？
8 what is the purpose of DLCIs in Frame Relay ? A they identify the logcal circuit between a local router and a frame relay WAN switch B they determine the frame relay encapsulation type C they represent the keepalives used to maintain the PVC in an active state D they represent the physical address of the router atteched to a Frme Relay network 应该是C吧？A好象应该是在一对路由器之间而不是和交换机之间啊
9 You just entered the following command "routers(config)#line console 0 " which Operation is most likely to follow ? A create a passWord on the console terminal line B change from configuration mode to console privilege mode 好象都不对啊，A之前应该有login啊，B的话，可是现在已经在这个模式下了啊
标准答案，请trust me 1。选A 自己做实验可以证实选A 2。C 这个很简单，楼主解释正确 3。A 有没有TELNET都是 LOCAL ETHERNET PORT 4。B 解释正确 5。B 建立网络地址 8。A C是LMI的性能 9。A 这个题出的有点SB 10。楼主解释正确 11。CONNECT是连接的意思，不代表什么程序 TELNET是程序啊
六.tk中有关广播地址的一道题 what is the broadcast address for this network 192.57.78.0/27. A.192.57.78.33 B 192.57.78.64 c 192.57.78.87 d 192.57.78.97 e 192.57.78.159 f 192.57.78.254 首先这是一个c类地址（default-subnet是/24 可以得到X=27-24=3(用于子网化），2^3-2=6个有效子网 M=8-3=5(用雨主机地址的分配，每个子网能提供2^5-2＝30个有效主机地址 而且可知道：有效子网为： 32，64，96，128，160，192 故可知广播地址为63，95，127，159，191，223
七.路由器相关 12.You telnet to a host on a remote network.which MAC address will be present in the ARP table when you issue the "show arp "command?
a.MAC address of the destination host Ethernet port b.MAC address of the local router ethernet port c.MAC address of the the destination router serial port d.MAC address of the local router serial port
标准答案：B 但（A）也有争议。
我的问题是： 1、假如是远程主机之间的通信，那么应该是对端的ROUTER的MAC地址呀？ （这个通信中到底有几个路由器呢，show arp说明我当前是在路由器上执行的操作，哪么怎么会还显示自己的MAC地址， “arp CACHE” 中不是仅显示外部来访网络设备的条目吗？假如是这样又怎么会是 B ，自己本地路由的 E0 MAC ）
2、每个网络设备应该只有一个MAC地址吧？路由也不例外是吧？ （B 和 D，这两项选顶中： D是不是根本就是一种障眼法呢？ 根本没有“路由的MAC地址是 serial port 的MAC 地址的说法，可以说路由的MAC就应该是路由的 Ethernet port 的MAC 地址，对吗？
九.黄金综合版上的一道题 359.a hosta in the sale department cant connect to the hostb in management department. choose the reason! routera(e0)-----------------------(e0)routerb 192.168.23.1 192.168.21.5
hosta hostb 192.168.23.2 192.168.21.2 255.255.240.0 255.255.255.240 A. the routerb inteface's ip addresss. B. hosta's bad ip address C.hostb's badd ip address D.bad broadcast address E.the routera interface's ip addresss. Answer:C 我怎么觉得ip都对呢？？？
