题目内容

帧中继网的虚电路建立在 (1) ,在用户层面采用的协议是 (2) 。这种网络没有流量控制功能,但增加了拥塞控制功能。如果沿着帧传送方向出现了拥塞,则把帧地址字段中的 (3) 位设置为1,这样接收方就可通过 (4) 协议要求发送方降低数据速率。最适合提供帧中继业务的网络是 (5) 。 1()

A. 数据链路层
B. 网络层
C. 传输层
D. 会话层

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配置WWW服务器是UNIX操作平台的重要工作之一,而Apach是目前应用最为广泛的Web服务器产品之一, (1) 是Apache的主要配置文件。URL根目录与服务器本地目录之间的映射关系是通过指令 (2) 设定;指令Server- Admin的作用是 (3) :而设置index.html或default.html为目录下默认文档的指令是 (4) ;如果允许以"http://www.xxx.edu.cn/~username"方式访问用户的个人主页,必须通过 (5) 指令设置个人主页文档所在的目录。 1()

A. httpd.conf
B. srm.conf
C. access.conf
D. apache.conf

信元是信元交换的单位。为控制差错,在信元中包括CRC校验和,其生成公式为 (1) ,校验和对 (2) 进行校验。信元交换采用 (3) 技术进行复用。在交换过程中,当实施VP交换时,其中VPI、VCI的变化情况是 (4) 。若在交换过程中出现拥塞,该信息被记录在信元的 (5) 中。 3()

A. TDM
B. FDM
C. WDM
D. ATDM

The purpose of the requirements definition phase is to produce a clear, complete, consistent, and testable (6) of the technical requirements for the software product. During the requirements definition phase, the requirements definition team uses an iterative process to expand a broad statement of the system requirements into a complete and detailed specification of each function that the software must perform and each (7) that it must meet. The starting point is usually a set of high level requirements from the (8) that describe the project or problem. In either case, the requirements definition team formulates an overall concept for the system and then defines (9) showing how the system will be operated publishes the system and operations concept document and conducts a system concept review(SCR). Following the SCR, the team derives (10) require merits for the system from the high level requirements and the system and operations conceptusing structured or object-oriented analysis, the team specifies the software functions and algorithms needed to satisfy each detailed requirement.

A. cotailed
B. outlined
C. total
D. complete

与线路交换相比,分组交换最大的优点是 (1) ,最大的缺点是 (2) 。设待传送数据总长度为L位分组长度为P位,其中头部开销长度为H位,源节点到目的节点之间的链路数为h,每个键路上的延迟时间为D秒,数据传输率为B bit/s,线路交换和虚电路建立连接的时间都为Ss,在分组交换方式下每个中间节点产生d bit的延迟时间,则传送所有数据,线路交换需时间为 (3) s,虚电路分组交换所需时间为 (4) s,数据报分组交换所需时间为 (5) s。([X]表示对X向上取整) 4()

A. S+(hd/B+P/B)×|L/(P-H)|
B. S+(hD+P/B)×[L/(P-H)]
C. S+[(h,-1)D+P/B]×[L/(P-H)]
D. S+[(h-1)d/B+hD+P/B]X×{L/(P-H)}

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