CCNA2-6-english.doc

What is the purpose of a routing protocol? It is used to build and maintain ARP tables. It provides a method for segmenting and reassembling data packets. It allows an administrator to devise an addressing scheme for the network. It allows a router to share information about known networks with other routers. It provides a procedure for encoding and decoding data into bits for packet forwarding. Why is fast convergence收敛 desirable适合 in networks that use dynamic routing protocols? Routers will not allow packets to be forwarded until the network has converged. Hosts are unable to access their gateway until the network has converged. Routers may make incorrect forwarding decisions until the network has converged. 在收敛之前，路由器可能做出不正确的转发。 Routers will not allow configuration changes to be made until the network has converged. In which situation would a company register 注册for its own autonomous 自治system number (ASN)? when the companys ISP adds connection points to the Internet when additional routers are added to the corporate internetwork when more than one interior routing protocol is used when the company uses two or more ISPs What term refers to a group of networks that uses the same internal routing policies and is controlled by a single administrative authority?被一个管理机构控制 Internet intranet virtual private network autonomous system 自治系统 Which protocol is an exterior外部 routing protocol? BGP EIGRP OSPF RIP What device enables an ISP to connect with other ISPs to transfer data? border gateway router边界网关路由 DSLAM web server interior router Which part of an IP packet does the router use to make routing decisions决定? source IP address source MAC address destination IP address destination MAC address What statement is true regarding an AS number自治系统号? AS numbers are controlled控制 and registered for Internet use. Interior routing protocols require registered AS numbers. ISPs require all customers to have registered AS numbers. All routers at an ISP must be assigned the same AS number. Which routing protocol is used to exchange交换 data between two different ISPs? BGP EIGRP OSPF RIP v2 Consider this routing table entry:R 172.16.1.0/24 120/1 via 200.1.1.1 00:00:27 Serial0/1 What type of route is this? a static route a default route a RIP route an OSPF route an EIGRP route a directly-connected route Refer to the exhibit. If all routers are running RIP and network 10.0.0.0 goes down断开, when will R3 learn that the network is no longer available? in 30 seconds in 60 seconds in 90 seconds immediately 立即 What information is included in RIPv2 routing updates that is not included in RIPv1 updates? metric subnet mask area identification hop count autonomous system number What two types of businesses would benefit from registering注册 as their own autonomous systems拥有自己的自治系统? (Choose two.) a home business with one ISP connection a global business with connections to multiple local ISPs多个本地ISP a medium-sized nationwide business with Internet connectivity through different ISPs a large enterprise with two connections to the same ISP a small ISP with a single Internet connection through a larger ISP Which two statements describe static routes? (Choose two.) They are created in interface configuration mode接口配置模式. They require manual reconfiguration to accommodate network changes. 当数据改变时，重新手动配置 They automatically become the default gateway of the router. They are identified in the routing table with the prefix S 在路由表中以S开头标示 They are automatically updated whenever an interface is reconfigured or shutdown. What is the difference between interior and exterior routing protocols?内部外部路由协议的的区别 Exterior routing protocols are only used by large ISPs. Interior routing protocols are used by small ISPs. Interior routing protocols are used to route on the Internet. Exterior routing protocols are used inside organizations. Exterior routing protocols are used to administer a single autonomous system. Interior routing protocols are used to administer several domains. Interior routing protocols are used to communicate within a single 单个autonomous system. Exterior routing protocols are used to communicate between multiple autonomous systems. Refer to the exhibit. Which configuration command项配置命令 or commands contributed建立 to the output that is shown? routerA(config-router)# no version 2 routerA(config)# interface fa0/0 routerA(config-if)# ip address 172.19.0.0 255.255.0.0 routerA(config-router)# network 192.168.3.0 routerA(config)# no ip default-gateway Refer to the exhibit. All of the routers are running RIP. There are two paths from router A to the 192.168.3.0 network. Based on the output of the show ip route command on router A, which route was entered into the routing table and why? A,B,C,D because it has the lowest administrative distance A,E,F,G,D because it has the lowest administrative distance A,B,C,D because it has the lowest metric最短距离 A,E,F,G,D because it has the lowest metric What is the purpose of the network command使用 network 命令有何作用in configuring RIP? to specify whether RIPv1 or RIPv2 will be used as the routing protocol to allow the router to monitor RIP updates that occur on other routers to identify the directly connected networks that will be announced in RIP updates 宣布直连路由 to configure the IP address on an interface that will use RIP to identify all of the remote networks that should be reachable from the router Refer to the exhibit. If connectivity between the two hosts is maintained, what is the maximum number of RIP routers that can be in the path from HostA to HostB? 在两个主机之间最多主机是多少 14 15 16 17 Refer to the exhibit.