6.在10BASET以太網(wǎng)系統(tǒng)中，利用集線器連接網(wǎng)絡(luò)，集線器的數(shù)量最多為（　　　）

A.2個                                                              B.3個

C.4個                                                              D.5個

7.對于單模光纜，在100Mbps傳輸速率，全雙工情況下，系統(tǒng)中最長的媒體段可達（　　�。�

A.1km                                                              B.2km

C.10km                                                            D.40km

8.全雙工以太網(wǎng)所采用的技術(shù)標(biāo)準(zhǔn)是（　　�。�

A.802.3a                                                          B.802.3i

C.802.3j                                                           D.802.3x

9.在FDDI的幀格式中，幀前導(dǎo)碼是為了建立同步，幀前導(dǎo)碼的長度為（　　　）

A.16bits                                                           B.32bits

C.64bits                                                           D.128bits

10.10BASE2以太網(wǎng)絡(luò)的拓撲結(jié)構(gòu)是（　　�。�

A.總線型                                                         B.星型

C.環(huán)型                                                             D.網(wǎng)狀型