单选题 In the following essay, each blank has four choices. Choose the most suitable one from the four choices and write down in the answer sheet.
Open Shortest Path First (OSPF) is a (36) routing algorithm that (37) work clone on the OSI IS-IS intradomain routing protocol. This routing, as compared to distance-vector routing, requires (38) processing power. The (39) algorithm is used to calculate routes. OSPF routing table updates only take place when necessary, (40) at regular intervals.

单选题 A. distance-vector B. link-state C. flow-based D. selective flooding
【正确答案】 B
【答案解析】
单选题 A. derived from B. deviated from C. was derived from D. was deviated from
【正确答案】 C
【答案解析】
单选题 A. more B. less C. same D. most
【正确答案】 A
【答案解析】
单选题 A. Bellman-Ford B. Ford-Fulkerson C. Dijkstra D. RIP
【正确答案】 C
【答案解析】
单选题 A. but rather B. rather too C. rather than D. rather that
【正确答案】 D
【答案解析】[解析] 开放最短路径优先算法(OSPF)是一种链路状态路由选择算法，它来自开放式系统互联(OSI)的中间系统对中间系统(IS-IS)域内路由选择协议方面的工作。与距离向量路由选择相比，链路状态路由选择需要的更多处理性能，但是却提供了对路由选择过程的更多控制和对改变情况更快的反应。采用Dijkstra算法来计算路由。 OSPF路由选择表只有在需要时，才进行修改，而不是每隔固定间隔就发生一次。这十分明显地减少了通信量。并且节省了网络带宽。