职业类 [单选] In multipoint networks , there are tree persistence methods when a station finds a channel busy.in the 1-persistent method,after the station finds the line idle,it sends its frame immediately.this method has the () chance of collision because two or more stations may find the line (请作答此空) and send their frames immediately. In the nonpersistent method , a station that has a frame to send () the line . If the line is idle , it sends immediately If the line is not idle , it waits a () amount of time and then senses the line again.The nonpersistent approach () the chance of collision because it is unlikely that two or more stations will wait the same amount of time and retry to send simultaneously The p-persistent approach combines the advantages of the other two strategies . It reduces the chance of collision and improves efficiency. 2022.01.24 查看答案
职业类 [单选] Together with the network layer,the transport layer is the heart of the protocol ().The network layer provides end-to-end () delivery using datagrams or virtual circuits.The transport layer builds on the network layer to provide data transport from a process on a (请作答此空) machine to a process on a destination machine with a desired level of reliability that is independent of the physical () currently in use.It provides the abstractions that applications nedd to use the network..Without the () layer,the whole concept of layered protocols would make little sense. 2022.01.24 查看答案
职业类 [单选] CSMA, although more efficient than ALOHA or slotted ALOHA, still has one glaring inefficiency. If the medium is busy, the station will wait for a random amount of time. When two frames collide, the medium remains () for the duration of transmission of both damaged frames. The use of random delays reduces the probability of(). For(请作答此空)frames, compared to propagation time, the amount of wasted capacity can be considerable. This waste can be reduced if a station continues to listen to the medium while().The maximum utilization depends on the length of the frame and on the() time; the longer the frames or the shorter the propagation time,the higher the utilization. 2022.01.24 查看答案
职业类 [单选] The Hypertext Transfer Protocol , the Web’s () protocol , is at the heart of the Web. HTTP is implemented in two programs : a () program and a server program . The client program and server program executing on different end systems , talk to each other by () HTTP messages . HTTP defines how Web clients request Web pages from servers and how servers transfer web pages to clients . when a user (请作答此空) a web page , the browser sends http request messages for the objects in the page to the server . The server () the requests and responds with http response messages that contain the objects . 2022.01.24 查看答案
职业类 [单选] work(),systems that effectively isolate an organization’s internal network structure from an () network, such as the INTERNET is becoming increasingly popular. These firewall systems typically act as application-layer(请作答此空)between networks, usually offering controlled TELNET, FTP, and SMTP access. With the emergence of more sophisticated()layer protocols designed to facilitate global information discovery , there exists a need to provide a general ()for these protocols to transparently and securely traverse a firewall. 2022.01.24 查看答案