问题 单项选择题

某PIX 525防火墙有如下配置命令,该命令的正确解释是 (22)
firewall (config) #static (inside,outside) 61.144.51.43 192.168.0.8

A.地址为61.144.51.43的外网主机访问内网时,地址静态转换为192.168.0.8

B.地址为61.144.51.43的内网主机访问外网时,地址静态转换为192.168.0.8

C.地址为192.168.0.8的外网主机访问外网时,地址静态转换为61.144.51.43

D.地址为192.168.0.8的内网主机访问外网时,地址静态转换为61.144.51.43

答案

参考答案:D

解析:[要点解析] static命令用于配置静态IP地址翻译,即从外网发起一个会话,会话的目的地址是一个内网的IP地址,static语句将把内部地址翻译成一个指定的全局地址,从而允许这个会话建立。该命令的配置语法如下。
static(internal_if_name,external_if_name) outside_ip_address inside_ip_address
其中,intema_if_name表示内部网络接口(例如inside),安全级别较高;external_if_name为外部网络接口(例如outside等),安全级别较低;outside_ip_address为外部网络接口上的IP地址;inside_ip_address为内部网络的本地IP地址。
可见,命令firewall(config)#static(inside,outside) 61.144.51.43 192.168.0.8可解释为:当地址为 192.168.0.8的内网主机访问外网时,地址静态转换为61.144.51.43。也可以理解成static命令创建了外部 IP地址61.144.51.43和内部IP地址192.168.0.8之间的静态映射。

单项选择题 A3型题
阅读理解

The way people hold to the belief that a fun - filled, pain free life equals happiness actually reduces their chances of ever attaining real happiness. If fun and pleasure are equal to happiness then pain must be equal to unhappiness. But in fact, the opposite is true: more often than not things that lead to happiness involve some pain.

As a result, many people avoid the very attempts that are the source of true happiness. They fear the pain inevitably brought by such things as marriage, raising children, professional achievement, religious commitment (预担的义务), self - improvement.

Ask a bachelor(单身汉) why he resists marriage even though he finds dating to be less and less satisfying. If he is honest he will tell you that he is afraid of making a commitment. For commitment is in fact quite painful. The single life is filled with fun, adventure, excitement. Marriage has such moments, but they are not its most distinguishing features.  

Couples with infant children are lucky to get a whole night’s sleep or a three - day vacation. I don’t know any parent who would choose the word fun to describe raising children. But couples who decide not to have children never know the joys of watching a child grow up or of playing with a grandchild.

Understanding and accepting that true happiness has nothing to do with fun is one of the most liberating realizations. It liberates time: now we can devote more hours to activities that can genuinely increase our happiness. It liberates money: buying that new car or those fancy clothes that will do nothing to increase our happiness now seems pointless. And it liberates us from envy: we now understand that all those who are always having so much fun actually may not be happy at all.

小题1:According to the author, a bachelor resists marriage chiefly because ________ .

A.he is reluctant to take on family responsibilities

B.he believes that life will be more cheerful if he remains single

C.he finds more fun in dating than in marriage

D.he fears it will put an end to all his fun adventure and excitement小题2:Raising children, in the author’s opinion is ________ .

A.a moral duty

B.a thankless job

C.a rewarding task

D.a source of inevitable pain小题3:From the last paragraph, we learn that envy sometimes stems from ________ .

A.hatred

B.misunderstanding

C.prejudice

D.ignorance小题4:To understand what true happiness is one must ________ .

A.have as much fun as possible during one’s lifetime

B.make every effort to liberate oneself from pain

C.put up with pain under all circumstances

D.be able to distinguish happiness from fun小题5:What is the author trying to tell us?

A.Happiness often goes hand in hand with pain.

B.One must know how to attain happiness.

C.It is important to make commitments.

D.It is pain that leads to happiness.