IPv6是下一代IP协议。IPv6的基本报头包含(32)个字节，此外还可以包含多今扩展报头。基本报头中的(33)字段指明了一个特定的源站向一个特定目标站发送的分组序列，各个路由器要对该分组序列进行特殊的资源分配，以满足应用程序的特殊传输需求。一个数据流由(34)命名。在IPv6中，地址被扩充为128位，并且为IPv4保留了一部分地址空间。按照IPv6的地址表示方法，以下地址中属于IPv4地址的是(35)。(36)是IPv6的测试床，实际上是一个基于IPv4的虚拟网络，用于研究和测试IPv6的标准、实现以及IPv4向IPv6的转变过程。

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In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

 How does the developer of a large database system achieve(71)and data independence? How does the developer make certain that stored items are(72)and do not simply disappear in the immensities of the database, as if in quicksand?

 One solution is to set up a(73)system, in which all data (the internal level), all records and files (the conceptual level), and all user interfaces (the external level) are controlled by one central programming group. This may seem the most useful solution. But worldwide enterprises such as the meteorological and satellite tracking networks, IBM, and General Motors gather and record information at a very large number of locations. To stay flexible and avoid top - heaviness, such an organization might want to avoid excessive centralization.

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In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

With the implementation of(66), the so - called network has become a reality. The provision of such facilities is the most important part of the network requirements. However, in many applications the communicating computers may be of different types. This means that they may use different programming languages and, more importantly, different forms of(67)interface between user(application) program, normally referred to, as application processes, and the underlying communication services may be(68). For example, one computer may be a small single - user computer, while another may be a large(69)system. In the earlier days of computer communication, these issues meant that only closed communities of computers (that is, from the same manufacturer) could communicate with each other in a meaningful way. IBM's Systems Network Architecture (SNA) and DEC's Digital Network Architecture (DNA) are just two examples of communication software packages produced by manufacturers to allow their systems to be interconnected together. These proprietary packages, however, of which there am still many inexistence, do not address the problem of universal interconnect ability, or open systems interconnection. In an attempt to alleviate this problem,(70), in the late 1970s, formulated a reference model to provide a common basis (or the coordination of standards developments and to allow existing and evolving standards activities to be placed into perspective with one another.

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