问题 单项选择题

网络拓扑设计器优劣将直接影响网络的性能、可靠性与( )。

A.设备种类
B.主机类型
C.网络协议
D.通信费用

答案

参考答案:D

解析: 计算机网络拓扑即通过网络中结点与通信线路之间的几何关系表示网络结构。拓扑设计是建设计算机网络的重要一步,也是实现各种网络协议的基础,它对网络性能、系统可靠性与通信费用都有重大影响。

问答题

One thing that distinguishes the online world from the real one is that it is very easy to find things. To find a copy of The Economist in print, one has to go to a newsstand, which may or may not carry it. Finding it online, though, is a different proposition. Just go to Google, type it in" economist" and you will be instantly directed to economist.com. (46) Indeed, until Google, now the world’s most popular search engine, came on to the scene in September 1998, searching online was a hit-or-miss affair.

Google was vastly better than anything that had come before: so much better, in fact, that it changed the way many people use the web. (47) Almost overnight, it made the web far more useful, particularly for non-specialist users, many of whom regard Google as the Internet’s front door. It’s now a worldwide phenomenon. Not only has it made the Internet into an extremely fast and valuable research tool, it’s become a common word and has even created a new verb" to google." (48)The recent fuss over Google’s stock market flotation obscures its far wider social significance: few technologies, after all, are so influential that their names have become a household verb such as the cloning technology creates the verb" to clone".

Google began in 1998 as an academic research project by Sergey Brin and Lawrence Page, who were then graduate students at Stanford University in Palo Alto, California. It was not the first search engine, of course. (49) Existing search engines were able to scan a large portion of the web, build an index, and then find pages that matched particular words, but were less good at presenting those pages, which might number in the hundreds of thousands, in a useful way.

Mr. Brin’s and Mr. Page’s accomplishment was to devise a way to sort the results by determining which pages were likely to be most relevant. They did so by using a mathematical program, called PageRank. (50) This program is at the heart of Google’s success, distinguishing it from all search engines and accounting for its apparently magical ability to find the most useful web pages. With this powerful ability. Google distinguished itself from among all the search engines and became an established standing research tool in the online world.

(50) This program is at the heart of Google’s success, distinguishing it from all search engines and accounting for its apparently magical ability to find the most useful web pages.

问答题