●SDLC was invented by IBM to replace the older Bisynchronous protocol for wide area connec

Question

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

(71) A．HDLC

B．Frame. Relay

C．X．25

D．X．21

(72) A．a peer to peer

B．a point-to-point

C．not a peer to peer

D．a peer to peers

(73) A．a primary station

B．one or more primary stations

C．a secondary station

D．one or more secondary stations

(74) A．a primary station

B．one or more primary stations

C．a secondary station

D．one or more secondary stations

(75) A．half duplex

B．full duplex

C．half or full duplex

D．half and full duplex

Answer 1

正确答案：A,C,A,D,B
【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。