第 1 套ISDN,which stands for Integrated Services Digital Network, is a system of digital phone connections, which has been available for over a decade.This system allows data to be transmitted simultaneously across the world using (1) digital connectivity.With ISDN,voice and data are carried by bearer channels occupying a bandwith of (2) (bits per second).Some switches limit B channels to capacity of 56 Kbps.A data channel (3) handles signaling at 16Kbps or 64Kbps,depending on (4) .Note that,in ISDN terminology,”k” means (5),and not 1024(210) as in many computer applications;therefore,a 64Kbps channel carries data at a rate of 64000bps. A new set of standard prefixes has recently been created to handle this. Under this scheme,”K”(Kilo) means 1000(103),”M” (Mega) means 1000000(106),and soon ,and “Ki”(Kibi) means 1024 (210),”Mi” (Mebi) means 1048576(220).and soon。 (1). A.Multi-ends B.circle C.indirect D.end-to-end (2). A.34 Kbps B. 84 Kbps C. 64 Kbps D. 54 Kbps (3). A.D channel B.A channel C.B channel D.C channel (4). A.the method B.the number C.the service type D.the user type (5). A.100000(105) B.1000(103) C.10000(104) D.100(102) 答案: 1:D,2:C,3:A,4:C,5:B 第 2 套Bluetooth is a universal radio interface in the (1) frequency band that enables portable celectronic devices (2) connect and communicate (3) via short range,ad hoc networks.Each unit can simultaneously communicate with up to (4) other units per piconet. Moreover,each unit can simultaneously (5) to several piconets,Bluetooth technology which apart from Ericsson,has gained the support of Nokia,IBM,Toshiba,Intel and many other manufactures,eliminates the need for wires,cables and connectors for and between cordless or mobile phones,modems,headsets,PDAs, Computes,printers,progjectors,local ares networks,and so on ,and paves the way for new and completely different devices and applications. (1). A.2.45GHz B. 4.45GHz C. 2.95GHz D. 3.45GHz (2). A.in B. on C. to D. with (3). A.narrowly B.wirelessly C.freely D.widely (4). A.use B.sever C.host D.base (5). A.relate B.add C.close D.belong 答案:1:A,2:C,3:B,4:B,5:D 第 3 套(1)is used to ensure the confidentiality,integrity and authenticity of the two end points in the private network .the(2),an application layer protocol,authenticates each peer in an IPsec transaction ,IKE negotiates security policy,determining which algorithm may be used to set up theRunnel .It also handles the exchang of session keys used for that one transaction.Networks that use (3)to secure data traffic can automatically authenticate devices by using (4)whichVerify the identities of the two users who are sending information back and forth .IPsec can be ideal way to secure data in large networks that require (5) connections among many devices。 (1) A.Encryption B.Code C.Certificate D. Tunnel (2) A.associated links B.Internet Key Exchange C IPsec D. encryption (3) A authenticity B.password C.IPsec D. Internet Key Exchange (4) A.protocols B.keywords C.IKE D. digital certificates (5) A.free B.strict C.secure D.remote 答案:1:A,2:B,3:C,4:D,5:C 第 4 套LAPB is a (1) protocol that provides complete data transparency in a (2)operation. It supports a peer-to-peer link in that neither end of the link plays the role of the permanent master station. HDLC LAPB is the (3)that is usually used by(4), the (5)standard for Packet Switched Networks. (1)Abit-oriented synchronous Bbyte-oriented synchronous Cbit-oriented asynchronous Dbyte-oriented asynchronous (2)Ahalf-duplex point-to-point Bhalf-duplex point-to-points Cfull-duplex point-to-point Dfull-duplex point-to-points (3)APhysical Layer BLink Layer CNetwork Layer DTransport Layer (4)AX.21 BX.25 CX.28 DX.29 (5)AITU BIEEE COSI DANSI 答案:1:A,2:C,3:B,4:B,5:A 第 5 套Data communications equipment(DEC) (1) the serial data stream from the DTE and converts it to some form of (2) suitable of transmission on voice grade lines. At the (3),the DCE performs the reverse function of convering the received analog signal to serial digital data stream .The simplest form of DCE is a (4) or data set . At the transmit end, the modem can be considered a form of (5),while at the receive end, it can be considered a form of analog to digital converter. The most common forms of modulation by modems are frequency shift keying(FSK),phase shift keying(PSK) ,and quadrature amplitude modulation(QAM). If the cables and signal levels used to interconnect the DTE and DCE were left unregulated,the variations generated would probably be proporation to the number of manufactures. Electronics Industries Association(EIA) ,an organization of manufactuuers concerned with establishing industry standards,have agreed on the RS-232C as the standard interface between the DTE and the modem .This is a 25 pin cable pins have designated