The de facto standard Application Program Interface (API) for TCP/IP applications is the “sockets” interface. Although this API was developed for （71） in the early 1960s it has also been implemented on a wide variety of no-Unix systems. TCP/IP （72） Writte

TCP/IP(71)layer protocols provide services to the application(72)running on a computer. The application layer does not define the application itself, but rather it defines(73)that applications need--like the ability to transfer a file in the case of HTTP. In short, the application layer provides an(74)between software running on a computer and the network itself. The TCP/IP application layer includes a relatively large number of protocols, with HTTP being only one of those. The TCP/IP(75)layer consists of two main protocol options--the Transmission Control Protocol(TCP) and the User Datagram Protocol(UDP).

A．application

B．transport

C．link

D．network

Each machine supporting TCP has a TCP transport entity, either a library procedure, a user process, or part of the kernel. In all case, it manages TCP streams and (71) to the IP layer. A TCP (72) accepts user data streams from local process, breaks them into pieces not exceeding 64KB, and sends each piece as a separate IP (73). When datagrams containing TCP data arrive at a machine, they are given to the TCP entity, which reconstructs the original byte streams.The IP layer gives no guarantee that datagrams will be delivered properly, so it is up to TCP to time out and (74) them as need be. Datagmms do arrive may well do so in the wrong order, it is also up to TCP to (75) them into messages in the proper sequence.

A．calls

B．interfaces

C．links

D．produces

A.Application Layer、PPP、TCP/IP、RLP，Physical Layer

B.Application Layer、PPP、RLP、TCP/IP、Physical Layer

C.Application Layer、RLP、PhysicalLayer、TCP/IP、PPP

D.Physical Layer、RLP、PPP、TCP/IP、Application Layer

Thedefacto standard Application Program Interface （API） for TCP/IP applications is the “sockets” interface. Although this API was developed for __（71）__ in the early 1980s it has also been implemented on a wide variety ofnon-Unix systems。 TCP/IP __（72）__ written using the sockets API have in the past enjoyed a high degreeof portability and we would like the same __（73）__ with IPv6 applications。 But changes are requiredto the sockets API to support IPv6 and this memo describes these changes。These include a new socket address structure to carry IPv6 __（74）__，new address conversion functions，and some new socket options。These extensions aredesigned to provide access to the basic IPv6 features required by TCP and UDPapplications，including multicasting， while introducing aminimum of change into the system and providing complete __（75）__ for existing IPv4 applications。

A.Windows

B.Linux

C.Unix

D.DOS@@@SXB@@@A.applications

B.networks

C.protocols

D.systems@@@SXB@@@A.portability

B.availability

C.capability

D.reliability@@@SXB@@@A.connections

B.protocols

C.networks

D.addresses@@@SXB@@@A.availability

B.compatibility

C.capability

D.reliability

● TCP/IP communication protocol contains four layers. From bottom to top, the four layers are __(71)__.

（71）A．network interface layer, internet layer, transport layer and application layer

B．internet layer, network interface layer, transport layer and application layer

C．network interface layer, transport layer, network interface layer and application layer

D．application layer, transport layer, internet layer and network interface layer

在Windows 98的网络组件中，某种组件是用于在各种不同平台上建立TCP/IP通信的API，应用程序利用这些API通过TCP/IP协议进行通信，这种组件是______。

Microsoft's COM is a software(71) that allows applications to be built from binary software components. COM is the underlying architecture that forms the foundation for higher-level software services, like those provided by OLE. COM defines a binary standard for function calling between components, a way for components to dynamically discover the interfaces implemented by other components, and a mechanism to identify components and their interfaces uniquely.

OLE is a compound(72) standard developed by Microsoft. OLE makes it possible to create(73) with one application and link or embed them in a second application. Embedded objects retain their original format and(74) to the application that created them. Support for OLE is built into the Windows and MacOS Operating Systems. A(75) compound document standard developed mainly by Apple and IBM is called OpenDoc.

A．structure

B．procedure

C．protocol

D．architecture

The de facto standard Application Program Interface (API) for TCP/IP applications is the “sockets” interface. Although this API was developed for （71） in the early 1960s it has also been implemented on a wide variety of no-Unix systems. TCP/IP （72） Written using the sockets API have in the past enjoyed a high degree of portability and we would like the same （73） with IPv6 applications. But changes are required to the sockets API to support IPv6 and this memo describes these changes. These include a new socket address structure to carry IPv6 （74） ,new address conversion functions, and some new socket options. These extensions are designed to provide access to the basic IPv6 features requited by TCP and UDP applications, including multicasting, while introducing a minimums of change into the system and providing complete （75） for existing IPv4 applications.

A.Windows

B.Linux

C.Unix

D.DOS

A transport layer protocol has several responsibilities. One is to create a process-to-process (program-to-program) communication; TCP uses port (71) to accomplish this. Another responsibility of a transport layer protocol is to create a (72) and error-control mechanism at the transport level. TCP uses a sliding (73) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve (74) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends (75) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.

（71）

A．numbers

B．connections

C．diagrams

D．resources

● TCP/IP （71） layer protocols provide services to the application （72） running on a computer. The application layer does not define the application itself, but rather it defines （73） that applications need—like the ability to transfer a file in the case of HTTP. In short, the application layer provides an （74） between software running on a computer and the network itself. The TCP/IP application layer includes a relatively large number of protocols, with HTTP being only one of those. The TCP/IP （75） layer consists of two main protocol options—the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).