For each blank，choose the best answer from the four choices and write down on the answer sheet.（ ）is a six bytes OSI layer 2 address which is burned into every networking device that provides its unique identity for point to point communication.（ ）is a professional organization of individuals in multiple professions which focuses on effort on lower-layer protocols.（请作答此空）functions with two layers of protocols.It Can connect networks of different speeds and can be adapted to an environment as it expands.（ ）is the popular LAN developed under the direction of the IEEE 802.5.（ ）is the popular backbone technology for transmitting information at high speed with a high level of fault tolerance which is developed under the direction of ANSI.A.The hubB.The bridgeC.The routerD.The proxy
For each blank，choose the best answer from the four choices and write down on the answer sheet.
（ ）is a six bytes OSI layer 2 address which is burned into every networking device that provides its unique identity for point to point communication.
（ ）is a professional organization of individuals in multiple professions which focuses on effort on lower-layer protocols.
（请作答此空）functions with two layers of protocols.It Can connect networks of different speeds and can be adapted to an environment as it expands.
（ ）is the popular LAN developed under the direction of the IEEE 802.5.
（ ）is the popular backbone technology for transmitting information at high speed with a high level of fault tolerance which is developed under the direction of ANSI.
（ ）is a six bytes OSI layer 2 address which is burned into every networking device that provides its unique identity for point to point communication.
（ ）is a professional organization of individuals in multiple professions which focuses on effort on lower-layer protocols.
（请作答此空）functions with two layers of protocols.It Can connect networks of different speeds and can be adapted to an environment as it expands.
（ ）is the popular LAN developed under the direction of the IEEE 802.5.
（ ）is the popular backbone technology for transmitting information at high speed with a high level of fault tolerance which is developed under the direction of ANSI.
A.The hub
B.The bridge
C.The router
D.The proxy
B.The bridge
C.The router
D.The proxy
参考解析
解析：MAC地址就是在媒体接入层上使用的地址，通俗点说就是网卡的物理地址，现在的MAC地址一般都采用6字节48bit。
IEEE是由多个研究底层协议的机构组成的权威组织。
以太网是共享介质的，物理层接收帧，如果地址和自己的地址一致（或者是广播消息），就留下；反之则转发。因此当主机的数量增加时，网络就会变得十分嘈杂，传送效率明显降低。而网桥是工作在数据链路层的设备，它将一个大型的以太网分为几个小网段，可以取得减少通信量的作用。
令牌环网是一种符合IEEE802.5标准的局域网。监督帧，即令牌，顺序地从一个网站传递到相临的网站上。希望获得网络访问权的网站必须等到令牌到达之后才能传输数据。
光纤分布数据接口是目前成熟的LAN技术中传输速率最高的一种。这种传输速率高达100Mb/s的网络技术所依据的标准是ANSIX3T9.5。该网络具有定时令牌协议的特性，支持多种拓扑结构，传输媒体为光纤。使用光纤作为传输媒体具有多种优点：
较长的传输距离，相邻站间的最大长度可达2km，最大站间距离为200km。
具有较大的带宽，FDDI的设计带宽为100Mbit/s。
具有对电磁和射频干扰抑制能力，在传输过程中不受电磁和射频噪声的影响，也不影响其他设备。
光纤可防止传输过程中被分接偷听，也杜绝了辐射波的窃听，因而是最安全的传输媒体。
IEEE是由多个研究底层协议的机构组成的权威组织。
以太网是共享介质的，物理层接收帧，如果地址和自己的地址一致（或者是广播消息），就留下；反之则转发。因此当主机的数量增加时，网络就会变得十分嘈杂，传送效率明显降低。而网桥是工作在数据链路层的设备，它将一个大型的以太网分为几个小网段，可以取得减少通信量的作用。
令牌环网是一种符合IEEE802.5标准的局域网。监督帧，即令牌，顺序地从一个网站传递到相临的网站上。希望获得网络访问权的网站必须等到令牌到达之后才能传输数据。
光纤分布数据接口是目前成熟的LAN技术中传输速率最高的一种。这种传输速率高达100Mb/s的网络技术所依据的标准是ANSIX3T9.5。该网络具有定时令牌协议的特性，支持多种拓扑结构，传输媒体为光纤。使用光纤作为传输媒体具有多种优点：
较长的传输距离，相邻站间的最大长度可达2km，最大站间距离为200km。
具有较大的带宽，FDDI的设计带宽为100Mbit/s。
具有对电磁和射频干扰抑制能力，在传输过程中不受电磁和射频噪声的影响，也不影响其他设备。
光纤可防止传输过程中被分接偷听，也杜绝了辐射波的窃听，因而是最安全的传输媒体。
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