and can be embedded into HTML pages, interpreted by JVM-capable browsers. A. JavaScript B. JavaBean C. Applet D. JSP
49. Which of the following best describes the function of the OSI reference model’s transport layer?
A. It sends data by using flow control B. It provides the best path for delivery C. It determines network addresses D. It provides error-correcting
50. What is the most efficient subnet mask to use on point-to-point WAN links? A. 255.255.255.0 B. 255.255.255.224 C. 255.255.255.252 D. 255.255.255.248
二、 Please choose true(Ｔ) or false( Ｆ) for the following questions (15 points) 1. Error-correcting and error-detecting are two types of technique in error control.
2. Link state dynamic routing algorithms operate by having each router maintain a table giving the best known distance to each destination and which line to use to get there. These tables are updated by exchanging information with the neighbors.
3. With Manchester encoding, each bit period is divided into two equal intervals. A binary 1 bit is sent by having the voltage set high during the first interval and low in the second one. A binary 0 is just the reverse: first low and then high.
4. A connection is established in TCP by means of the two-way handshake.
5. The range of frequencies transmitted without being strongly attenuated is called bandwidth. 6. Shannon’s major result is that the maximum data rate of a noisy channel whose bandwidth is H Hz, and whose signal-to-noise ratio is S/N, is given by Maximum number of baud/sec = H log2 (1+S/N)
7. Two different switching techniques are widely used nowadays: circuit switching and packet switching.
8. The protocols used to determine who goes next on a multi-access channel belong to a sub-layer of the data link layer called the LLC sublayer.
9. The basic function of RTP is to multiplex several real-time data streams onto a single stream of UDP packets.
10. The Internet solution is to realize that two potential problems exist network capacity and receiver capacity and to deal with each of them separately. To do so, each sender maintains two windows: the window the receiver has granted and a second window, the congestion window.
11. Selective repeat, is for the receiver simply to discard all subsequent frames, sending no acknowledgments for the discarded frames.
12. The IPSec is a set of open standards that provides data confidentiality, data integrity, and authentication between participating peers at the IP layer. 13. B2C, the full name is Business to Company.
14. One type of person-to-person communication often goes by the name of end-to-end communication, to distinguish it from the client-server model.
15. An issue that occurs at every level is how to keep a fast sender from swamping a slow received with data. This subject is called flow control.