问题 问答题

希赛公司的一个分支机构被分配了一个C类地址192.168.36.0/24,该分支机构现在需要分配IP地址的有财务、人力资源、销售、审计、计划、服务6个部门,每个部门一个子网,每个部门的机器数量不超过25台。请回答以下问题。

为给这6个部门分配IP地址,请问子网掩码是多少,每个子网有多少个地址,可以分配的地址有多少

答案

参考答案:考虑到每个部门的机器数量不超过25台,每个部门子网大小就划为32个IP地址,其中一个网络地址,一个广播地址,可以分配的地址有30个,子网掩码是255.255.255.112。

解析:子网掩码是相对特定的IP地址而言的,如果脱离了IP地址就毫无意义。它的出现跟着一个特定的IP地址,用来为计算这个IP地址中的网络号部分和主机号部分提供依据。换句话说,就是在写一个IP地址后,再指明哪些是网络号部分、哪些是主机号部分。子网掩码的格式与IP地址相同,对应的网络号部分用1填上,主机号部分用0填上。
此问题考查IP地址的划分,IP地址的划分根据子网大小或子网个数来确定划分的规模。
题目中告诉我们,每个部门的机器数量不超过25台,因此可以将每个部门子网大小划为32个IP地址,除去全0和全1外,还有30个IP地址可以分配,足够一个部门使用了。这样,主机号应该为5位(25=32),而网络号为27位,由此可以得到子网掩码为11111111.11111111.11111111.11100000,转化为十进制数后为255.255.255.224。

问答题 简答题
阅读理解

     If English means endless new words, difficult grammar and sometimes strange pronunciation, you are

wrong. Haven't you noticed that you have become smarter since you started to learn a language?

     According to a new study by a British university, learning a second language can lead to an increase in

your brain power. Researchers found that learning other languages changes grey matter. This is the area

of the brain which processes information. It is similar to the way that exercise builds muscles.

     The study also found the effect is greater when the younger people learn a second language.

     A team led by Dr. Andrea Mechelli, from University College London, took a group of Britons who

only spoke English. They were compared with a group of "early bilinguals" who had learnt a second

language before the age of five, as well as a number of later learners.

     Scans showed that grey matter density (密度)in the brain was greater in bilinguals than in people

without a second language. But the longer a person waited before mastering a new language, the smaller

the difference is.

     "Our findings suggest that the structure of the brain is changed by the experience of learning a second

language," said the scientists.

     It means that the change itself increases the ability to learn.

     Professor Dylan Vaughan Jones of the University of Wales, has researched the link between

bilingualism and maths skills. "Having two languages gives you two windows in the world and makes the

brain more flexible (灵活的)," he said. "You are actually going beyond language and have a better

understanding of different ideas."

     The findings were matched in a study of native Italian speakers who had learned English as a second

language between the ages of 2 and 34. Reading, writing, and comprehension were all tested. The results

showed that the younger they started to learn, the better they will do it. "Studying a language means you

get an entrance to another world," explained the scientists.

1. The main subject talked about in this passage is________.

A. science on learning a second language

B. man's ability of learning a second language

C. language can help brain power

D. language learning and maths study

2. We may know from the scientific findings that________.

A. the earlier you start to learn a second language, the greater the grey matter

density is

B. there is no difference between a later second language learner and one who doesn't know a second

language

C. the experience of learning a second language has bad effect on people's brain

D. the ability of learning a second language is changing all the time

3. In the last two paragraphs,the author wants to tell us that________.

A. learning a second language is the same as studying maths

B. early learning of a second language helps you a great deal in studying other subjects

C. Italian is the best choice for you as a second language

D. you'd better choose the ages between 2 and 34 to learn a second language