IPv6的地址長度是_(1)_，它的基本首部長度固定為_(2)_。為了加快路由器處理數(shù)據(jù)報的速度，IPv6首部取消了_(3)_字段，而通過數(shù)據(jù)鏈路層和運輸層來完成差錯檢驗功能。為了便于地址閱讀，IPv6使用_(4)_記法。在IPv4向IPv6過渡的方案中，當IPv6數(shù)據(jù)報進入IPv4網(wǎng)絡時，將IPv6數(shù)據(jù)報封裝成為IPv4數(shù)據(jù)報進行傳輸?shù)姆桨笗r_(5)_。

　�、臕.32位 B.64位 C.128位 D.256位

　　⑵A.20字節(jié) B.40字節(jié) C.60字節(jié) D.256字節(jié)

　�、茿.校驗和 B.差錯控制 C.流量控制 D.糾錯

　�、華.冒號十六進制B.十進制 C.冒號八進制 D.二進制

　　⑸A.雙協(xié)議站 B.多協(xié)議棧 C.協(xié)議路由器 D.隧道技術 答案：CBAAD

　　The Integrated Services Digital Network(ISDN) is a set of international standards for access to advanced,all-digital public _(1)_network.

　　ISDN standards have been defined by the _(1)_,a branch of the United Nations’ Internaational Telecommunications Union (ITU), in the series I and Q recommendations.

　　There are five ISDN Standard Devices.A_(1)_ is any piece of communicating equipment that complies with the ISDN standard. _(1)_performs the logical interface functions of switching and local-device control. _(1)_performs the physical interface conversion between the dissimilar customer and network sides of the interface.

　�、臕.information B.telecommunications C.global D.local

　�、艫.ITU-T B.ITU-U C. ITU-A D. ITU-R

　�、洽娶葾.TA B.TE C.NT1 D.NT2 E.ET Answer：BABCD