问题 单项选择题

有一个公司内部网络发生了故障,故障现象是:甲用户可以正常使用内部服务器和互联网服务,乙用户无法使用这些服务。那么检测故障最佳的方法是:()。

A.从乙用户所在的物理网络的物理层开始检查故障,依次检测物理层、数据链路层、网络层直到应用层

B.从乙用户所在的物理网络的路由器开始检查故障,依次检测路由器,二层交换机、中继器或HUB

C.从检测公司的服务器开始,依次检测服务器、网络互联设备、物理层连接

D.从甲用户所在的物理网络首先开始检测,依次检测物理层、数据链路层、网络层直到应用层

答案

参考答案:A

解析:

本题考查综合的故障检测能力。

在一个公司内部,有人能访问内部服务器和外部服务器,有人不能访问。此时应判断出应用层(对应各种服务)和网络层(外部网络和公司内部网络的公共部分)很有可能是可靠的;而问题很有可能出现在乙用户自己本身或者乙用户所在的网络区域。因此最佳方法是从乙用户的物理层开始检测,依次为物理层、数据链路层、网络层直至应用层。

阅读理解

阅读短文,选择正确答案。

      Now satellites are helping to forecast (预报) the weather. They are in space, and they can reach any part

of the world. The satellites take pictures of the atmosphere (大气), because this is where the weather forms

(形成). They send these pictures to the weather stations. So meteorologists (气象学家) can see the

weather of any part of the world. From the pictures, the scientists can often say how the weather will change.

      Today, nearly five hundred weather stations in sixty countries receive satellite pictures. When they receive

new pictures, the meteorologists compare (比较) them with earlier ones. Perhaps they may find that the clouds

have changed during the last few hours. This may mean that the weather on the ground may soon change, too.

In their next weather forecast, the meteorologists can say this.

      So the weather satellites are a great help to the meteorologists. Before satellites were invented, the scientists

could forecast the weather for about 24 or 48 hours. Now they can make good forecasts for three or five days.

Soon, perhaps, they may be able to forecast the weather for a week or more ahead (提前).

1. Satellites travel _______. [ ]

A. in space

B. in the atmosphere

C. above the ground

D. above space

2. Why do we use the weather satellites to take pictures of the atmosphere? Because _______. [ ]

A. the weather satellites can do it easily

B. clouds form there

C. the weather forms there

D. the pictures can forecast the weather

3. Meteorologists forecast the weather _______. [ ]

A. when they have received satellite pictures

B. after they have compared new satellite pictures with earlier ones

C. before they received satellite pictures

D. during they study satellite pictures

4. Maybe we'll soon be able to forecast the weather for _______. [ ]

A. one day

B. two days

C. five days

D. seven days or even longer

5. The main (主要的) idea of this passage is that satellites are now used in _______. [ ]

A. taking pictures of the atmosphere

B. receiving pictures of the atmosphere

C. doing other work in many ways

D. weather forecasting

单项选择题