问题 填空题

图4是一台主机上用Sniffer捕捉的数据包,请根据显示的信息回答下列问题。

该主机上设置的DNS服务器的IP地址是()

答案

参考答案:211.81.20.200

解析:

标号为5的数据包是主机发送到网站服务器的syn(syn=j)包等待服务器确认,主机进入SYN SEND状态,等待服务器确认;标号为6的数据包是确认客户的SYN(ack=j+1),同时自己也发送一个SYN(syn=k)包,即SYN+ACK包,此时服务器进入SYN_RECV状态。

阅读理解

阅读理解。

     "Our aim is to take our art to the world and make people understand what it is to move," said David

Belle, the founder of parkour(跑酷).

     Do you love running? It is a good exercise, yet many people find it boring. But what if making your

morning jog a creative one? Like jumping from walls and over gaps, and ground rolls? Just like the James Bond in the movie Casino Royale? Bond jumps down from a roof to a windowsill and then runs several

blocks over obstacles on the way. It is just because of Bond's wonderful performances that the sport has

become popular worldwide.

     Yes, that's parkour, an extreme street sport aimed at moving from one point to another as quickly as

possible, getting over all the obstacles in the path using only the abilities of the human body. Parkour is

considered an extreme sport. As its participants dash around a city, they may jump over fences, run up

walls and even move from rooftop to rooftop.

     Parkour can be just as exciting and charming as it sounds, but its participants see parkour much more

than that.

     Overcoming all the obstacles on the course and in life is part of the philosophy(理念)behind parkour.

This is the same as life. You must determine your destination, go straight, jump over all the barriers as if in parkour and never fall back from them in your life to reach the destination successfully. A parkour lover

said, "I love parkour because its philosophy has become my life, my way to do everything."

     Another philosophy we've learnt from parkour is freedom. It can be done by anyone, at any time,

anywhere in the world. It is a kind of expression of trust in yourself. It is only a state of mind. It is when

you trust yourself that you earn energy.

1.Parkour has become popular throughout the world because of ________.

A.its founder, David Belle

B.the film, Casino Royale

C.its risks and tricks

D.the varieties of participants

2.The underlined word "obstacles" in Paragraph 2 is closest in meaning to "________".

A.streets  

B.objects  

C.barriers  

D.roofs

3.Which of the following is true of parkour?

A.It challenges human abilities.

B.It is a good but boring sport.

C.It needs special training.

D.It is a team sport.

4.As its participants move around a city, ________.

A.they can ask for help

B.they may choose to escape

C.they should run to extremes

D.they must learn to survive

填空题