问题 单项选择题

防火墙的工作层次是决定防火墙效率及安全的主要因素,下面的叙述中正确的是()

A.防火墙工作层次越低,则工作效率越高,同时安全性越高

B.防火墙工作层次越低,则工作效率越低,同时安全性越低

C.防火墙工作层次越高,则工作效率越高,同时安全性越低

D.防火墙工作层次越高,则工作效率越低,同时安全性越高

答案

参考答案:D

解析:

本题考查防火墙的基础知识。

防火墙的性能及特点主要由以下两方面所决定:

①工作层次,这是决定防火墙效率及安全的主要因素。一般来说,工作层次越低,则工作效率越高,但安全性就低了;反之,工作层次越高,工作效率越低,则安全性越高。

②防火墙采用的机制,如果采用代理机制,则防火墙具有内部信息隐藏的特点,相对而言,安全性高,效率低;如果采用过滤机制,则效率高,安全性却降低了。

单项选择题
阅读理解

Will it matter if you don’t take your breakfast?A short time ago,a test was given in the United States.People of different ages from 12 to 83 were asked to have a test.During the test,these people were given all kinds of breakfasts,and sometimes they got no breakfast at all.Scientists wanted to see how well their body worked when they had eaten different kinds of breakfasts.

The results show that if he or she eats a right breakfast,he or she will work better than if he or she has no breakfast.If a student has fruit,eggs,bread and milk before going to school,he will learn more quickly and listen more carefully in class.

The result is opposite to what some people think.Having no breakfast will not help you lose weight.This is because people become so hungry at noon that they eat too much for lunch.They will gain weight instead of losing it.You will lose more weight if you reduce your other meals.

64.During the test,the people were given          .

A.no breakfast at all   B.very rich breakfast

C.different foods or sometimes none   D.little food for breakfast

65.The results show that          .

A.breakfast has little to do with a person’s work

B.breakfast has a great effect on work and studies

C.a person will work better if he only was fruit and milk

D.girl students should have less for breakfast

66.Which of the following is NOT true?

A.It is bad for your health to have no breakfast

B.Too little for breakfast and too much for lunch may make you fatter

C.If you don’t eat much for lunch and supper,you may lose weight

D.The more breakfast you have,the more quickly you’ll learn in class