【判断题】The Internet offers a range of services to users.

The diffserv approach to providing QoS in networks employs a small, well-defined set of building blocks from which you can build a variety of( ). Its aim is to define the differentiated services (DS) byte, the Type of Service (ToS) byte from the Internet Protocol Version 4 ( )and the Traffic Class byte from IP Version 6, and mark the standardized DS byte of the packet such that it receives a particular forwarding treatment, or per-hop behavior (PHB), at each network node. The diffserv architecture provides a( )within which service providers can offer customers a range of network services, each differentiated based on performance. A customer can choose the ( )level needed on a packet-by-packet basis by simply marking the packet&39;s Differentiated Services Code Point (DSCP) field to a specific value.This ( ) specifies the PHB given to the packet within the service provider network.

A.servicesB.UsersC.networksD.structuresA.messageB.PacketC.headerD.packageA.informationB.StructureC.meansD.frameworkA.performanceB.SecureC.privacyD.dataA. packetB.valueC.serviceD.paragraph

The diffserv approach to providing QoS in networks employs a small, well-defined set of building blocks from which you can build a variety of(). Its aim is to define the differentiated services (DS) byte, the Type of Service (ToS) byte from the Internet Protocol Version 4 ()and the Traffic Class byte from IP Version 6, and mark the standardized DS byte of the packet such that it receives a particular forwarding treatment, or per-hop behavior (PHB), at each network node. The diffserv architecture provides a()within which service providers can offer customers a range of network services, each differentiated based on performance. A customer can choose the ()level needed on a packet-by-packet basis by simply marking the packet&39;s Differentiated Services Code Point (DSCP) field to a specific value.This () specifies the PHB given to the packet within the service provider network.

A.servicesB.UsersC.networksD.structuresA.messageB.PacketC.headerD.packageA.informationB.StructureC.meansD.frameworkA.performanceB.SecureC.privacyD.dataA. packetB.valueC.serviceD.paragraph

is a multimedia Internet service that allows users to traverse the Internet by moving from one document to another via links that connect them together.

A．FTP

B．WWW

C．E-mail

D．TCP

【填空题】Each Internet （1）, called a host, is independent. Its operators can choose which （2） services to use and which （3） services to make available to the （4） Internet community. Remarkably, this anarchy by design works exceedingly well. IP is responsible for moving packet of data from （5） to node. IP forwards each packet based on a four-byte destination （6） (the IP address). The Internet authorities assign ranges of numbers to different organizations, The organizations （7） groups of their numbers to departments. （8） is responsible for verifying the correct delivery of data from （9） to server. Data can be lost in the intermediate （10）. TCP adds support to detect error or lost data and to trigger retransmission until the data is correctly and completely received.

A webcam is a digital camera that sends video images to other computer users. It’s about the 【C1】______ of a golf ball and typically 【C2】______ on top of your computer monitor. Once the webcam is 【C3】______ to the USB port of your computer with the necessary software, 【C4】______ images of you can be sent to one or more users over the Internet 【C5】______ an instant messaging(IM) service.

A webcam costs about $50. More expensive models come with added 【C6】______ , such as better picture resolution. Two leading makers, Logitech and Creative, offer a range of models, 【C7】______ software is included. There is no extra Internet 【C8】______ to send or receive video images, though you’ll have to 【C9】______ for a free instant messaging service. Everyone can see and hear one another in 【C10】______ time. Grandparents can see their grandkids more 【C11】______ Webcams can work with almost any computer bought in the past five years and can 【C12】______ long distance phone bills.

【C13】______ you have broadband, that is, a high-speed cable-modem or DSL connection, images may 【C14】______ a long time to download, 【C15】______ a slide show rather than a movie. While webcams are easy to link to your computer, learning to 【C16】______ the software can take time. You have to make. some rearrangement with the configurations.

【C17】______ you have a 56k modem and the people you want to 【C18】______ won’t mind seeing live shots instead of perfect video, a webcam is still fun, 【C19】______ before you buy, be sure everyone, 【C20】______ for the same IM service.

【C1】

A．weight

B．size

C．volume

D．space