12) What is an autonomous system (什么是自治系统)？
A. An area
B. A domain
C. A contiguous set of routers defined within a larger internetwork, that do not share routing information with the external internetwork
D. All of the above
E. None of the above
13) What is a default route (什么是默认路由)？
A. A type of static route
B. A destination for any nonroutable packet
C. Gateway of last resort
D. All of the above
E. None of the above
14) What type of information does a distance vector router build its routing table with (距离向量路由器用何种类型的信息来建立它的路由选择表)？
A. 呼叫packets
B. Second-hand information
C. LSPs
D. First-hand information
15) What is the count to infinity problem (什么是无限计数问题)？
A. A routing loop that results from the way distance vector protocols use second-hand information
B. The inability of routers to process more than 16 hops
C. The excessive CPU overhead presented by distance vector algorithms
D. The result of using both RIP and IGRP on the same internetwork
16) What is poison reverse (什么是破坏逆转)？
A. A change to the default update period timer
B. A routing loop that occurs when using second-hand information to update route tables
C. A router virus
D. A version of split-horizon that sends back a “route unreachable” update to the router that the route was learned from, in order to avoid routing loops
17) What is RIP (什么是R I P )？
A. RIP is an older distance vector Interior Gateway Protocol with a 30-second update timer and . maximum of 15 hops (where “i n f i n i t y” is 16 hops)
B. RIP is a new link-state protocol created by Cisco
C. RIP is a proprietary protocol created by Cisco that has two versions; only version 2 is used currently
D. RIP is a distance vector Interior Gateway Protocol with a 224 maximum network diameter (maximum 224 hops)
18) What is IGRP (什么是I G R P )？
A. IGRP is an older distance vector Interior Gateway Protocol with a 30-second update timer and a maximum of 15 hops (where infinity is 16 hops)
B. IGRP is a new link-state protocol created by Cisco
C. IGRP is a proprietary protocol created by Cisco that has two versions; only version 2 isused currently
D. IGRP is a distance vector and Interior Gateway Protocol with a 224 maximum network diameter (maximum 224 hops)
19) What is the purpose of a flash update in IGRP (IGRP中的瞬时更新的目的是什么)？
A. A flash update is a standard 90-second update
B. After three flash updates, a route is considered unreachable
C. A flash update is sent immediately upon a change in the network topology, in order to speed convergence
D. After seven flash updates, a route is removed from the routing table
20) How can the administrator change how IGRP selects routes (管理员如何修改I G R P选择路由的方法)？
A. The administrator can set update timers
B. The administrator can enable or disable split horizon
C. The administrator can set up load balancing across redundant routes
D. The administrator can adjust the metric weights used for determining the route selection
21) The way to get traffic from one segment of the network to another segment is (在网段之间进行通信的方法是)：
A. Bridging
B. Routing
C. Switching
D. All of the above
22) Routing occurs at which layer (路由发生在哪一层)？
A. Physical layer
B. Data link layer
C. Network layer
D. Transport layer
23) In general, the bets route selected by a router is one with (一般而言，路由器选择的最佳路由具有何种特性)？
A. Least cost
B. Shortest distance
C. Lowest metric value
D. None of the above
24) A routing table typically includes which of the following (路由表通常包含下列的哪些信息)？
A. Destination network address
B. The total number of networks
C. The number of nodes in each network
D. The total number of routers in a network
