问题 填空题

如果借用C类IP地址中的3位主机号部分划分子网,则子网掩码应该为______。(请采用点分十进制法表示]

答案

参考答案:255.255.224

解析:对于标准的C类IP地址来说,标准予网掩码为255.255.255.0,即用32位IP地址的前24位标识网络号,后8位标识主机号。因此,每个C类网络下共可容纳254台主机。现在,考虑借用3位的主机号来充当子网络号的情形。为了借用原来8位主机号中的前3位充当子网络号,采用了新的、非标准子网掩码255.255.255.224(224的由来:224=(11100000)2),采用了新的子网掩码后,借用的3位子网号可以用来标识6个子网,分别为:001、010、011、100、101、110子网(子网号不能全为0或1,因此000、111子网不能用)。

阅读理解

People often said Thomas Edison was the greatest genius of his age. There are only a few men in all of history, who have changed the lives of other men as much as the inventor of the first useful electric light. But Edison could never be pleased only because someone said he was a genius. "There is no such thing as genius," Edison said. He thought what people called genius was mostly hard work.

But Edison was a dreamer as well as a worker. From his earliest days as a child he wondered about the secrets of nature. He tried to understand them, and then he tried to learn what he could usefully do with them.

Edison enjoyed thinking. He knew that most people would do almost anything instead of the difficult work of thinking, especially if they do not think very often. But he knew, too, that thinking could give men enjoyment and pleasure.

Edison could not understand how anyone could not be interested in life. As he loved to think, he also loved to work. On the day he became 75 years old, someone asked him what idea he had about life. “Work,” he answered, “Discovering the secrets of nature and using them to make men happier.” He said he had enough inventions in his mind to give him another 100 years of work.

小题1:According to Thomas Edison, what's genius?

A.Hard thinking.

B.Useful inventions

C.Useful dreams.

D.Hard work.小题2:After exploring the secrets of nature, Edison always tried to______.

A.make them useful in life

B.carry out a new experiment

C.write down what he had learnt

D.share them with others小题3:Edison could not understand______.

A.how anybody enjoyed life

B.how anybody loved working

C.why anybody loved thinking

D.why anybody was tired of life小题4:The underlined sentence in the last paragraph means that______.

A.Edison was able to live another 100 years

B.life was too short for Edison to work for human beings

C.Edison was born to be a great inventor

D.Edison was ready to make his l00th invention

单项选择题