单选题 SDLC was invented by IBM to replace the older Bisynchronous protocol for wide area connections between IBM equipment . A varietion of the{{U}} {{U}} 71 {{/U}} {{/U}}protocol called NRM is essentially the same as SDLC. SDLC is{{U}} {{U}} 72 {{/U}} {{/U}}protocol like HDLC, Frame Relay or X.25. An SDLC network is made up of{{U}} {{U}} 73 {{/U}} {{/U}}that controls all communications, and{{U}} {{U}} 74 {{/U}} {{/U}}. It is capable of{{U}} {{U}} 75 {{/U}} {{/U}}operation, but almost all practical applications are strictly half duplex.

单选题

A. HDLC
B. Frame Relay
C. X.25
D. X.21

【正确答案】 A

【答案解析】

单选题

A. a peer to peer
B. a point-to-point
C. not a peer to peer
D. a peer to peers

【正确答案】 C

【答案解析】

单选题

A. a primary station
B. one or more primary stations
C. a secondary station
D.one or more secondary stations

【正确答案】 A

【答案解析】

单选题

A. a primary station
B. one or more primary stations
C. a secondary station
D. one or more secondary stations

【正确答案】 D

【答案解析】

单选题

A. half duplex
B. full duplex
C. half or full duplex
D. half and full duplex

【正确答案】 B

【答案解析】[解析] SDLC是IBM用来连接广泛区域的IBM设备而发明的。另一重变化了的协议HDLC称为NRM，它与SDLC特别相似。SDLC跟 HDLC、帧中继和X.25一样不是点对点协议，一个SDLC网络由一些控制网络通信及从站的主站组成。它是全双工的，但实际上很多应用都是半双工的。